Leetcode3 ongest Substring without repeating characters

Just start also a variety of optimization, afraid of n*n time complexity also pass, again want to be able to simplify, and finally found a brute force directly AC, I overestimate it ...

Test instructions is to give you a string to find the string of the eldest son, but this substring is a rule, that is, there is no repetition of the character, I started from the first character to Traverse to the last character, because the longest substring must be one of the characters to start, I counted the oldest string is OK,   In fact, I have thought about it, this is actually not n*n time complexity, because the number of characters have limited, so the most is n*255 around, but this situation is still impossible, so I know, why violence can be too. ^-^

#include "stdio.h" #include "stdlib.h" #include "string" #include "string.h" using namespace Std;class solution {public:    int lengthoflongestsubstring (string s) {    int i,j;        int len = S.size ();        int str[300];        int num,max=0;        for (i=0;i<len;i++)        {            Num = 0;            memset (str,0,sizeof (str));            for (j=i;j<len;j++)            {                if (str[s[j]]==0)                    {                        num++;                        str[s[j]]=1;                    }                else break                    ;            }            if (Num>max)            {                max = Num;            }        }        printf ("%d\n", max);        return max;    }; int main () {solution test;string s = "eeee"; test.lengthoflongestsubstring (s); return 0;}

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Leetcode3 ongest Substring without repeating characters