【28】Implement strStr()

Implement strStr().

Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

直接暴力做就好了

int strStr(string haystack, string needle) {
int len1=haystack.length();
int len2=needle.length();
for(int i=0;i<=len1-len2;i++){
bool flag=true;
for(int j=0;j<len2;j++){
if(haystack[i+j]!=needle[j]){flag=false;break;}
}
if(flag)return i;
}
return -1;
}