LeetCode 3. Longest Substring Without Repeating Characters

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

Examples:

Given "abcabcbb", the answer is "abc", which the length is 3.

Given "bbbbb", the answer is "b", with the length of 1.

Given "pwwkew", 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.

 

 

1,使用哈希表查目标子序列，暴力拆解，不快

int lengthOfLongestSubstring(char* s) {
    char table[128] = {NULL};
    for(int i = 0;i < 128;i++)
    {
        table[i] = 0;
    }
    char *p = s;
    char *q = s;
    int MaxLength = 0;
    int TempLength = 0;
    if(p == NULL)
    {
        return MaxLength;
    }
    while(*p)
    {
        if(table[*p] == 1)
        {
            q++;
            p = q;
            TempLength = 0;
            for(int i = 0;i < 128;i++)
            {
                table[i] = 0;
            }
        }
        TempLength++;
        if(TempLength > MaxLength)
        {
            MaxLength = TempLength;
        }
        table[*p] = 1;
        p++;
    }
    return MaxLength;
}

 

 2，妙解抄录

用地址建表

int lengthOfLongestSubstring(char* s)
{
    int len=0;
    char *end=s,*temp;
    char* addressTable[128]={NULL};
    while(*end){
        temp = addressTable[*end];
        addressTable[*end]=end;
        if(temp>=s){
        len=end-s>len?end-s:len;
        s = temp+1;
        }end++;
    }
    len=end-s>len?end-s:len;
    return len;
}