LeetCode-3. Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters.

Example 1:

Input: "abcabcbb"
Output: 3 
Explanation: The answer is "abc", with the length of 3. 

Example 2:

Input: "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3:

Input: "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3. 
             Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

题解：

动态记录上一次不重复点

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        int prev = -1, res = 0;
        int len = s.length();
        vector idx(200, -1);
        for (int i = 0; i < len; i++) {
            if (idx[s[i]] != -1) {
                prev = max(prev, idx[s[i]]);
            }
            res = max(res, i - prev);
            idx[s[i]] = i;
        }
        return res;
    }
};