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.

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/longest-substring-without-repeating-characters
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

C语言的一个题解

int lengthOfLongestSubstring(char * s){
    int prior = 0; //上次状态下最长子串的长度
    int left = 0;
    int dict[256] = {0}; //映射ASCII码
    int right = 1; //表示字符串中第right个字符
    int i;
    while(*s != '\0'){
        i = *s-0; //字符转换为整数
        if(dict[i] > left) left = dict[i];
        dict[i] = right;
        prior = (prior>right-left)?prior:right-left; //right的值比对应的数组下标大1
        s++;
        right++;
    }
    return prior;
}

  1. if(dict[i] > left) left = dict[i];后面出现重复的就更新了

  2. dict[i] = right;每次都是当前值

  3. prior = (prior>right-left)?prior:right-left; //right的值比对应的数组下标大1