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// 28. Find the Index of the First Occurrence in a String
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
* given two strings 'needle' and 'haystack', return index of the first
* occurrence of 'needle' in 'haystack', or -1 if 'needle' is not part of
* 'haystack'
*/
int cmp(char *s, int i, char *p, int n_bytes) {
int j = 0;
while (n_bytes--) {
if (*(s + i) != *(p + j))
return -1;
++i;
++j;
}
return 0;
}
int strStr(char *haystack, char *needle) {
int s_len = strlen(haystack), n_len = strlen(needle);
if (!s_len) {
if (!n_len)
return 0;
return -1;
}
if (!n_len)
return 0;
int err = 0;
for (int i = 0; i < s_len; ++i) {
if (haystack[i] == needle[0]) {
err = cmp(haystack, i, needle, n_len);
if (err)
continue;
return i;
}
}
return -1;
}
int main() {
char hs1[] = "sadbutsad", n1[] = "sad";
char hs2[] = "leetcode", n2[] = "leeto";
printf("%d\n", strStr(hs1, n1)); // expect: 0
printf("%d\n", strStr(hs2, n2)); // expect: 0
}
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