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update: 添加问题“3442.奇偶频次间的最大差值I”的代码和题解(#979)
* 3442: WA.cpp (#978) what? 这能WA Signed-off-by: LetMeFly666 <[email protected]> * 3442: AC.cpp (#978) - AC,100.00%,77.93% 注意判最小偶的时候要满足非零 Signed-off-by: LetMeFly666 <[email protected]> * 3442: AC.Cpp+Py+Go{Java (#978) int数组竟然也能 for(int t : a) cpp - AC,35.86%,85.52% py - AC,77.03%,77.03% go - AC,100.00%,62.50% java - AC,100.00%,57.67% Signed-off-by: LetMeFly666 <[email protected]> * MGJW+words: many (#978) * update: 添加问题“3442.奇偶频次间的最大差值I”的代码和题解(#979) Signed-off-by: LetMeFly666 <[email protected]> --------- Signed-off-by: LetMeFly666 <[email protected]>
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‎Codes/3442-maximum-difference-between-even-and-odd-frequency-i.cpp‎

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/*
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* @Author: LetMeFly
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* @Date: 2025-06-10 23:07:14
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* @LastEditors: LetMeFly.xyz
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* @LastEditTime: 2025-06-10 23:14:08
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*/
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#if defined(_WIN32) || defined(__APPLE__)
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#include "_[1,2]toVector.h"
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#endif
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class Solution {
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public:
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int maxDifference(string s) {
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int cnt[26] = {0};
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for (char c : s) {
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cnt[c - 'a']++;
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}
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int a1 = 0, a2 = 100;
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for (int c : cnt) {
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if (c % 2) {
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a1 = max(a1, c);
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} else if (c) {
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a2 = min(a2, c);
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}
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}
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return a1 - a2;
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}
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};

‎Codes/3442-maximum-difference-between-even-and-odd-frequency-i.go‎

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/*
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* @Author: LetMeFly
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* @Date: 2025-06-10 23:07:14
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* @LastEditors: LetMeFly.xyz
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* @LastEditTime: 2025-06-10 23:20:56
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*/
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package main
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func maxDifference(s string) int {
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cnt := [26]int{}
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for _, c := range s {
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cnt[c - 'a']++
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}
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a1, a2 := 0, 100
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for _, t := range cnt {
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if t % 2 == 1 {
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a1 = max(a1, t)
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} else if t > 0 {
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a2 = min(a2, t)
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}
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}
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return a1 - a2
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}

‎Codes/3442-maximum-difference-between-even-and-odd-frequency-i.java‎

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/*
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* @Author: LetMeFly
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* @Date: 2025-06-10 23:07:14
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* @LastEditors: LetMeFly.xyz
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* @LastEditTime: 2025-06-10 23:40:04
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*/
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class Solution {
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public int maxDifference(String s) {
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int[] cnt = new int[26];
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for (char c : s.toCharArray()) {
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cnt[c - 'a']++;
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}
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int a1 = 0, a2 = 100;
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for (int t : cnt) {
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if (t % 2 == 1) {
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a1 = Math.max(a1, t);
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} else if (t > 0) {
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a2 = Math.min(a2, t);
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}
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}
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return a1 - a2;
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}
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}

‎Codes/3442-maximum-difference-between-even-and-odd-frequency-i.py‎

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'''
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Author: LetMeFly
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Date: 2025-06-10 23:07:14
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LastEditors: LetMeFly.xyz
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LastEditTime: 2025-06-10 23:18:45
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'''
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from collections import Counter
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class Solution:
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def maxDifference(self, s: str) -> int:
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cnt = Counter(s)
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return max(v for v in cnt.values() if v % 2) - min(v for v in cnt.values() if v % 2 == 0)

‎README.md‎

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986986
|3375.使数组的值全部为K的最少操作次数|简单|<a href="https://leetcode.cn/problems/minimum-operations-to-make-array-values-equal-to-k/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2025/04/09/LeetCode%203375.%E4%BD%BF%E6%95%B0%E7%BB%84%E7%9A%84%E5%80%BC%E5%85%A8%E9%83%A8%E4%B8%BAK%E7%9A%84%E6%9C%80%E5%B0%91%E6%93%8D%E4%BD%9C%E6%AC%A1%E6%95%B0/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/147104288" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/minimum-operations-to-make-array-values-equal-to-k/solutions/3646138/letmefly-3375shi-shu-zu-de-zhi-quan-bu-w-i71e/" target="_blank">LeetCode题解</a>|
987987
|3392.统计符合条件长度为3的子数组数目|简单|<a href="https://leetcode.cn/problems/count-subarrays-of-length-three-with-a-condition/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2025/04/29/LeetCode%203392.%E7%BB%9F%E8%AE%A1%E7%AC%A6%E5%90%88%E6%9D%A1%E4%BB%B6%E9%95%BF%E5%BA%A6%E4%B8%BA3%E7%9A%84%E5%AD%90%E6%95%B0%E7%BB%84%E6%95%B0%E7%9B%AE/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/147603015" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/count-subarrays-of-length-three-with-a-condition/solutions/3665081/letmefly-3392tong-ji-fu-he-tiao-jian-cha-h935/" target="_blank">LeetCode题解</a>|
988988
|3396.使数组元素互不相同所需的最少操作次数|简单|<a href="https://leetcode.cn/problems/minimum-number-of-operations-to-make-elements-in-array-distinct/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2025/04/08/LeetCode%203396.%E4%BD%BF%E6%95%B0%E7%BB%84%E5%85%83%E7%B4%A0%E4%BA%92%E4%B8%8D%E7%9B%B8%E5%90%8C%E6%89%80%E9%9C%80%E7%9A%84%E6%9C%80%E5%B0%91%E6%93%8D%E4%BD%9C%E6%AC%A1%E6%95%B0/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/147080178" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/minimum-number-of-operations-to-make-elements-in-array-distinct/solutions/3644951/letmefly-3396shi-shu-zu-yuan-su-hu-bu-xi-glg4/" target="_blank">LeetCode题解</a>|
989+
|3442.奇偶频次间的最大差值I|简单|<a href="https://leetcode.cn/problems/maximum-difference-between-even-and-odd-frequency-i/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2025/06/10/LeetCode%203442.%E5%A5%87%E5%81%B6%E9%A2%91%E6%AC%A1%E9%97%B4%E7%9A%84%E6%9C%80%E5%A4%A7%E5%B7%AE%E5%80%BCI/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/148570777" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/maximum-difference-between-even-and-odd-frequency-i/solutions/3697605/letmefly-3442qi-ou-pin-ci-jian-de-zui-da-nwwx/" target="_blank">LeetCode题解</a>|
989990
|剑指Offer0047.礼物的最大价值|简单|<a href="https://leetcode.cn/problems/li-wu-de-zui-da-jie-zhi-lcof/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2023/03/08/LeetCode%20%E5%89%91%E6%8C%87%20Offer%2047.%20%E7%A4%BC%E7%89%A9%E7%9A%84%E6%9C%80%E5%A4%A7%E4%BB%B7%E5%80%BC/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/129408765" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/li-wu-de-zui-da-jie-zhi-lcof/solutions/2155672/letmefly-jian-zhi-offer-47li-wu-de-zui-d-rekb/" target="_blank">LeetCode题解</a>|
990991
|剑指OfferII0041.滑动窗口的平均值|简单|<a href="https://leetcode.cn/problems/qIsx9U/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2022/07/16/LeetCode%20%E5%89%91%E6%8C%87%20Offer%20II%200041.%20%E6%BB%91%E5%8A%A8%E7%AA%97%E5%8F%A3%E7%9A%84%E5%B9%B3%E5%9D%87%E5%80%BC/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/125819216" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/qIsx9U/solution/by-tisfy-30mq/" target="_blank">LeetCode题解</a>|
991992
|剑指OfferII0091.粉刷房子|中等|<a href="https://leetcode.cn/problems/JEj789/" target="_blank">题目地址</a>|<a href="https://blog.letmefly.xyz/2022/06/25/LeetCode%20%E5%89%91%E6%8C%87%20Offer%20II%200091.%20%E7%B2%89%E5%88%B7%E6%88%BF%E5%AD%90/" target="_blank">题解地址</a>|<a href="https://letmefly.blog.csdn.net/article/details/125456885" target="_blank">CSDN题解</a>|<a href="https://leetcode.cn/problems/JEj789/solution/letmefly-jian-zhi-offer-ii-091fen-shua-f-3olz/" target="_blank">LeetCode题解</a>|

‎Solutions/LeetCode 3442.奇偶频次间的最大差值I.md‎

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---
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title: 3442.奇偶频次间的最大差值 I：计数
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date: 2025-06-10 23:41:55
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tags: [题解, LeetCode, 简单, 哈希表, 字符串, 计数]
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categories: [题解, LeetCode]
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---
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# 【LetMeFly】3442.奇偶频次间的最大差值 I：计数
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力扣题目链接：[https://leetcode.cn/problems/maximum-difference-between-even-and-odd-frequency-i/](https://leetcode.cn/problems/maximum-difference-between-even-and-odd-frequency-i/)
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<p>给你一个由小写英文字母组成的字符串&nbsp;<code>s</code> 。请你找出字符串中两个字符的出现频次之间的 <strong>最大</strong> 差值，这两个字符需要满足：</p>
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<ul>
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<li>一个字符在字符串中出现 <strong>偶数次</strong> 。</li>
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<li>另一个字符在字符串中出现 <strong>奇数次</strong>&nbsp;。</li>
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</ul>
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<p>返回 <strong>最大</strong> 差值，计算方法是出现 <strong>奇数次</strong> 字符的次数 <strong>减去</strong> 出现 <strong>偶数次</strong> 字符的次数。</p>
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<p>&nbsp;</p>
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<p><b>示例 1：</b></p>
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<div class="example-block">
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<p><span class="example-io"><b>输入：</b>s = "aaaaabbc"</span></p>
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<p><b>输出：</b>3</p>
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<p><b>解释：</b></p>
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<ul>
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<li>字符&nbsp;<code>'a'</code>&nbsp;出现 <strong>奇数次</strong>&nbsp;，次数为&nbsp;<code><font face="monospace">5</font></code><font face="monospace"> ；字符</font>&nbsp;<code>'b'</code>&nbsp;出现 <strong>偶数次</strong> ，次数为&nbsp;<code><font face="monospace">2</font></code>&nbsp;。</li>
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<li>最大差值为&nbsp;<code>5 - 2 = 3</code>&nbsp;。</li>
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</ul>
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</div>
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<p><b>示例 2：</b></p>
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<div class="example-block">
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<p><span class="example-io"><b>输入：</b>s = "abcabcab"</span></p>
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<p><b>输出：</b>1</p>
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<p><b>解释：</b></p>
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<ul>
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<li>字符&nbsp;<code>'a'</code>&nbsp;出现 <strong>奇数次</strong>&nbsp;，次数为&nbsp;<code><font face="monospace">3</font></code><font face="monospace"> ；字符</font>&nbsp;<code>'c'</code>&nbsp;出现 <strong>偶数次</strong>&nbsp;，次数为&nbsp;<font face="monospace">2 。</font></li>
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<li>最大差值为&nbsp;<code>3 - 2 = 1</code> 。</li>
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</ul>
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</div>
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<p>&nbsp;</p>
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<p><b>提示：</b></p>
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<ul>
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<li><code>3 &lt;= s.length &lt;= 100</code></li>
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<li><code>s</code>&nbsp;仅由小写英文字母组成。</li>
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<li><code>s</code>&nbsp;至少由一个出现奇数次的字符和一个出现偶数次的字符组成。</li>
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</ul>
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## 解题方法：计数
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遍历一遍字符串，统计出每种字符的出现次数。
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遍历英文单词的每种字符：
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+ 若这种字符出现次数为奇数次，则更新a1的值
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+ 否则若这种字符出现次数大于0，则更新a2的值
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最终返回$a_1-a_2$。
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+ 时间复杂度$O(len(s)+C)$，其中$C=26$
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+ 空间复杂度$O(C)$
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### AC代码
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#### C++
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```cpp
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/*
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* @Author: LetMeFly
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* @Date: 2025-06-10 23:07:14
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* @LastEditors: LetMeFly.xyz
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* @LastEditTime: 2025-06-10 23:14:08
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*/
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class Solution {
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public:
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int maxDifference(string s) {
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int cnt[26] = {0};
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for (char c : s) {
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cnt[c - 'a']++;
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}
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int a1 = 0, a2 = 100;
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for (int c : cnt) {
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if (c % 2) {
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a1 = max(a1, c);
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} else if (c) {
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a2 = min(a2, c);
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}
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}
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return a1 - a2;
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}
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};
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```
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#### Python
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```python
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'''
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Author: LetMeFly
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Date: 2025-06-10 23:07:14
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LastEditors: LetMeFly.xyz
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LastEditTime: 2025-06-10 23:18:45
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'''
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from collections import Counter
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class Solution:
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def maxDifference(self, s: str) -> int:
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cnt = Counter(s)
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return max(v for v in cnt.values() if v % 2) - min(v for v in cnt.values() if v % 2 == 0)
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```
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#### Java
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```java
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/*
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* @Author: LetMeFly
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* @Date: 2025-06-10 23:07:14
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* @LastEditors: LetMeFly.xyz
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* @LastEditTime: 2025-06-10 23:40:04
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*/
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class Solution {
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public int maxDifference(String s) {
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int[] cnt = new int[26];
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for (char c : s.toCharArray()) {
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cnt[c - 'a']++;
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}
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int a1 = 0, a2 = 100;
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for (int t : cnt) {
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if (t % 2 == 1) {
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a1 = Math.max(a1, t);
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} else if (t > 0) {
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a2 = Math.min(a2, t);
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}
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}
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return a1 - a2;
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}
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}
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```
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#### Go
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```go
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/*
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* @Author: LetMeFly
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* @Date: 2025-06-10 23:07:14
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* @LastEditors: LetMeFly.xyz
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* @LastEditTime: 2025-06-10 23:20:56
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*/
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package main
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func maxDifference(s string) int {
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cnt := [26]int{}
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for _, c := range s {
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cnt[c - 'a']++
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}
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a1, a2 := 0, 100
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for _, t := range cnt {
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if t % 2 == 1 {
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a1 = max(a1, t)
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} else if t > 0 {
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a2 = min(a2, t)
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}
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}
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return a1 - a2
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}
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```
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> 同步发文于[CSDN](https://letmefly.blog.csdn.net/article/details/148570777)和我的[个人博客](https://blog.letmefly.xyz/)，原创不易，转载经作者同意后请附上[原文链接](https://blog.letmefly.xyz/2025/06/10/LeetCode%203442.%E5%A5%87%E5%81%B6%E9%A2%91%E6%AC%A1%E9%97%B4%E7%9A%84%E6%9C%80%E5%A4%A7%E5%B7%AE%E5%80%BCI/)哦~
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>
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> 千篇源码题解[已开源](https://github.com/LetMeFly666/LeetCode)

‎Solutions/Other-English-LearningNotes-SomeWords.md‎

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|plume|n. 羽毛，飘升之物，一缕，(常用作装饰的)连在一起的羽毛<br/>v. 用羽毛装饰，(鸟)整理(羽毛)，借衣服修饰，自夸|
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|||
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|indefinitely|adv. 无期限的|
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|||
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|prayer|n. 祷告，祈祷文，经文|
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|better-off|adj. 比较富裕的，境况较好的|
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<p class="wordCounts">单词收录总数</p>
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‎Solutions/Other-Japanese-LearningNotes.md‎

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|お兄さん(おにいさん)|哥哥|
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|姉妹(しまい)|姐妹|
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|兄弟(きょうだい)|兄弟|
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|従兄弟/従姉妹(いとこ)|堂表兄弟姐妹|
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|かれ|他|
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|たち|们|
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|だれ|谁|

tryGoPy/MGJW/toRename/.gitignore renamed to tryGoPy/MGJW/lastWeek/12/.gitignore

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tryGoPy/MGJW/toRename/chat.md renamed to tryGoPy/MGJW/lastWeek/12/chat.md

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