Implement strstr Problem & Solution
Implement strstr(). Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
See the implement strstr problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")
static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
class Solution {
public:
int strStr(string haystack, string needle) {
if (needle.empty()) {
return 0;
}
for (int i = 0; i <= (int)(haystack.size() - needle.size()); ++i) {
bool ok = true;
for (int j = 0; j < needle.size(); ++j) {
ok &= haystack[i + j] == needle[j];
if (!ok) {
break;
}
}
if (ok) {
return i;
}
}
return -1;
}
};