Amazon Interview Question (Longest Subscrting without repeating chars)

Author: rachitiitr

LeetCode/1.two-sum.cpp

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+/*
+ * @lc app=leetcode id=1 lang=cpp
+ *
+ * [1] Two Sum
+ */
+
+// @lc code=start
+#include<bits/stdc++.h>
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        map<int, int> id;
+        for(int i = 0; i < nums.size(); i++) {
+            int make = target - nums[i];
+            if(id[make]) {
+                return {id[make]-1, i};
+            }
+            id[nums[i]] = i+1;
+        }
+        return {-1, -1};
+    }
+};
+// @lc code=end
+

LeetCode/3.longest-substring-without-repeating-characters.cpp

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+/*
+ * @lc app=leetcode id=3 lang=cpp
+ *
+ * [3] Longest Substring Without Repeating Characters
+ */
+
+// @lc code=start
+class Solution {
+public:
+    int lengthOfLongestSubstring(string s) {
+        int n = s.size();
+        if(s.size()==0)return 0;
+        int i,j;
+        i=0, j=0;
+        vector<int> cnt(326, 0);
+        cnt[s[0]]++;
+        int ans=1;
+        while(1){
+            if(j==n-1) break;
+            if(cnt[s[j+1]] == 0) j++, cnt[s[j]]++, ans=max(ans,j-i+1);
+            else {
+                cnt[s[i++]]--;
+            }
+        }
+        return ans;
+    }
+};
+// @lc code=end
+

LeetCode/7.reverse-integer.cpp

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+/*
+ * @lc app=leetcode id=7 lang=cpp
+ *
+ * [7] Reverse Integer
+ */
+
+// @lc code=start
+class Solution {
+public:
+    int reverse(int x) {
+        long long rev = 0;
+        long long limit = (1LL<<31);
+        while(x) {
+            int d = x%10;
+            x /= 10;
+            rev = 10*rev + d;
+        }
+        if(rev >= limit or rev < -limit) 
+            return 0;
+        return rev;
+    }
+};
+// @lc code=end
+