|
| 1 | +--- |
| 2 | +title: 2264.字符串中最大的 3 位相同数字 |
| 3 | +date: 2025-01-08 15:48:37 |
| 4 | +tags: [题解, LeetCode, 简单, 字符串] |
| 5 | +--- |
| 6 | + |
| 7 | +# 【LetMeFly】2264.字符串中最大的 3 位相同数字:遍历 |
| 8 | + |
| 9 | +力扣题目链接:[https://leetcode.cn/problems/largest-3-same-digit-number-in-string/](https://leetcode.cn/problems/largest-3-same-digit-number-in-string/) |
| 10 | + |
| 11 | +<p>给你一个字符串 <code>num</code> ,表示一个大整数。如果一个整数满足下述所有条件,则认为该整数是一个 <strong>优质整数</strong> :</p> |
| 12 | + |
| 13 | +<ul> |
| 14 | + <li>该整数是 <code>num</code> 的一个长度为 <code>3</code> 的 <strong>子字符串</strong> 。</li> |
| 15 | + <li>该整数由唯一一个数字重复 <code>3</code> 次组成。</li> |
| 16 | +</ul> |
| 17 | + |
| 18 | +<p>以字符串形式返回 <strong>最大的优质整数</strong> 。如果不存在满足要求的整数,则返回一个空字符串 <code>""</code> 。</p> |
| 19 | + |
| 20 | +<p><strong>注意:</strong></p> |
| 21 | + |
| 22 | +<ul> |
| 23 | + <li><strong>子字符串</strong> 是字符串中的一个连续字符序列。</li> |
| 24 | + <li><code>num</code> 或优质整数中可能存在 <strong>前导零</strong> 。</li> |
| 25 | +</ul> |
| 26 | + |
| 27 | +<p> </p> |
| 28 | + |
| 29 | +<p><strong>示例 1:</strong></p> |
| 30 | + |
| 31 | +<pre> |
| 32 | +<strong>输入:</strong>num = "6<em><strong>777</strong></em>133339" |
| 33 | +<strong>输出:</strong>"777" |
| 34 | +<strong>解释:</strong>num 中存在两个优质整数:"777" 和 "333" 。 |
| 35 | +"777" 是最大的那个,所以返回 "777" 。 |
| 36 | +</pre> |
| 37 | + |
| 38 | +<p><strong>示例 2:</strong></p> |
| 39 | + |
| 40 | +<pre> |
| 41 | +<strong>输入:</strong>num = "23<em><strong>000</strong></em>19" |
| 42 | +<strong>输出:</strong>"000" |
| 43 | +<strong>解释:</strong>"000" 是唯一一个优质整数。 |
| 44 | +</pre> |
| 45 | + |
| 46 | +<p><strong>示例 3:</strong></p> |
| 47 | + |
| 48 | +<pre> |
| 49 | +<strong>输入:</strong>num = "42352338" |
| 50 | +<strong>输出:</strong>"" |
| 51 | +<strong>解释:</strong>不存在长度为 3 且仅由一个唯一数字组成的整数。因此,不存在优质整数。 |
| 52 | +</pre> |
| 53 | + |
| 54 | +<p> </p> |
| 55 | + |
| 56 | +<p><strong>提示:</strong></p> |
| 57 | + |
| 58 | +<ul> |
| 59 | + <li><code>3 <= num.length <= 1000</code></li> |
| 60 | + <li><code>num</code> 仅由数字(<code>0</code> - <code>9</code>)组成</li> |
| 61 | +</ul> |
| 62 | + |
| 63 | + |
| 64 | + |
| 65 | +## 解题方法:遍历 |
| 66 | + |
| 67 | +使用一个变量记录最大的优质整数的字符,遍历字符串并不断更新这个最大值即可。 |
| 68 | + |
| 69 | ++ 时间复杂度$O(len(num))$ |
| 70 | ++ 空间复杂度$O(1)$ |
| 71 | + |
| 72 | +### AC代码 |
| 73 | + |
| 74 | +#### C++ |
| 75 | + |
| 76 | +```cpp |
| 77 | +/* |
| 78 | + * @Author: LetMeFly |
| 79 | + * @Date: 2025-01-08 15:25:00 |
| 80 | + * @LastEditors: LetMeFly.xyz |
| 81 | + * @LastEditTime: 2025-01-08 15:33:22 |
| 82 | + */ |
| 83 | +class Solution { |
| 84 | +public: |
| 85 | + string largestGoodInteger(string& num) { |
| 86 | + char M = '/'; // ASCII在0前一个 |
| 87 | + for (int i = 2; i < num.size(); i++) { |
| 88 | + if (num[i] == num[i - 1] && num[i] == num[i - 2]) { |
| 89 | + M = max(M, num[i]); |
| 90 | + } |
| 91 | + } |
| 92 | + return M == '/' ? string() : string(3, M); |
| 93 | + } |
| 94 | +}; |
| 95 | +``` |
| 96 | +
|
| 97 | +#### Python |
| 98 | +
|
| 99 | +```python |
| 100 | +''' |
| 101 | +Author: LetMeFly |
| 102 | +Date: 2025-01-08 15:34:27 |
| 103 | +LastEditors: LetMeFly.xyz |
| 104 | +LastEditTime: 2025-01-08 15:36:15 |
| 105 | +''' |
| 106 | +class Solution: |
| 107 | + def largestGoodInteger(self, s: str) -> str: |
| 108 | + M = '/' |
| 109 | + for i in range(2, len(s)): |
| 110 | + if s[i] == s[i - 1] == s[i - 2]: |
| 111 | + M = max(M, s[i]) |
| 112 | + return '' if M == '/' else M * 3 |
| 113 | +``` |
| 114 | + |
| 115 | +#### Java |
| 116 | + |
| 117 | +```java |
| 118 | +/* |
| 119 | + * @Author: LetMeFly |
| 120 | + * @Date: 2025-01-08 15:37:06 |
| 121 | + * @LastEditors: LetMeFly.xyz |
| 122 | + * @LastEditTime: 2025-01-08 15:41:37 |
| 123 | + */ |
| 124 | +class Solution { |
| 125 | + public String largestGoodInteger(String num) { |
| 126 | + char M = '/'; |
| 127 | + for (int i = 2; i < num.length(); i++) { |
| 128 | + if (num.charAt(i) == num.charAt(i - 1) && num.charAt(i) == num.charAt(i - 2)) { |
| 129 | + M = (char) Math.max(M, num.charAt(i)); |
| 130 | + } |
| 131 | + } |
| 132 | + return M == '/' ? "" : "" + M + M + M; |
| 133 | + } |
| 134 | +} |
| 135 | +``` |
| 136 | + |
| 137 | +#### Go |
| 138 | + |
| 139 | +```go |
| 140 | +/* |
| 141 | + * @Author: LetMeFly |
| 142 | + * @Date: 2025-01-08 15:43:44 |
| 143 | + * @LastEditors: LetMeFly.xyz |
| 144 | + * @LastEditTime: 2025-01-08 15:46:23 |
| 145 | + */ |
| 146 | +package main |
| 147 | + |
| 148 | +func largestGoodInteger(num string) string { |
| 149 | + M := byte('/') |
| 150 | + for i := 2; i < len(num); i++ { |
| 151 | + if num[i] > M && num[i] == num[i - 1] && num[i] == num[i - 2] { |
| 152 | + M = num[i] |
| 153 | + } |
| 154 | + } |
| 155 | + if M == '/' { |
| 156 | + return "" |
| 157 | + } |
| 158 | + return string(M) + string(M) + string(M) |
| 159 | +} |
| 160 | +``` |
| 161 | + |
| 162 | +> 同步发文于CSDN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/2025/01/08/LeetCode%202264.%E5%AD%97%E7%AC%A6%E4%B8%B2%E4%B8%AD%E6%9C%80%E5%A4%A7%E7%9A%843%E4%BD%8D%E7%9B%B8%E5%90%8C%E6%95%B0%E5%AD%97/)哦~ |
| 163 | +> |
| 164 | +> Tisfy:[https://letmefly.blog.csdn.net/article/details/145011261](https://letmefly.blog.csdn.net/article/details/145011261) |
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