diff options
Diffstat (limited to 'idx_first_occur_str.c')
-rw-r--r-- | idx_first_occur_str.c | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/idx_first_occur_str.c b/idx_first_occur_str.c new file mode 100644 index 0000000..3b09c26 --- /dev/null +++ b/idx_first_occur_str.c @@ -0,0 +1,49 @@ +// 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 +} |