[Sliding window] [leetcode] [medium] 3. The longest substring without repeated characters

topic:

Given a string, please find out the length of the longest substring  that does not contain repeated characters  .

Example:

输入: s = "abcabcbb"
输出: 3 
解释: 因为无重复字符的最长子串是"abc"，所以其长度为3

Original title address:

3. The longest substring without repeated characters

Problem-solving ideas:

Define two pointers left and right to move to the right respectively. When right points to a character, move left; otherwise, move right.

int lengthOfLongestSubstring(char * s){
    int exist[256] = {0};
    char *left = s;
    char *right = s;
    int max = 0;
    while (*right != 0) {
        if (exist[*right] == 1) {
            exist[*left++] = 0; // 移除左侧字符，left右移
        } else {
            exist[*right++] = 1; // 记录该字符，right右移
            int t = right - left;
            if (t > max) max = t;
        }
    }
    return max;
}