一、C++
class Solution {
public:
int strStr(string haystack, string needle) {
if (needle.size() == 0)
return 0;
int res = -1;
for (int i = 0; i < haystack.size(); i++)
{
for (int j = 0; j < needle.size(); j++) {
if (haystack[i] != needle[j]) {
break;
}
if (haystack.size() - i < needle.size())
return -1;
int temp = i;
while (temp < haystack.size() && j < needle.size() && haystack[temp] == needle[j]) {
temp++;
j++;
}
if (j >= needle.size())
return i;
else
break;
}
}
return res;
}
};