/*

Implement strStr() Total Accepted: 5346 Total Submissions: 26470 My Submissions

Implement strStr().

Returns a pointer to the first occurrence of needle in haystack, or null if needle is not part of haystack.

*/

class Solution {

public:

char *strStr(char *haystack, char *needle) {

int s1 = 0;

int s2 = 0;

while(haystack[s1] != '\0') s1++;

while(needle[s2] != '\0') s2++;

if(s1 == 0 && s2 == 0) return needle;

if(s2 == 0) return haystack;

for(int i = 0; i < s1 - s2 + 1; i++){

if(haystack[i] == needle[0]){

int count = 0;

while(haystack[i + count] == needle[count]){

count++;

if(count == s2){

return &haystack[i];

}

}

}

}

return NULL;

}

};