strStr.go

package strStr

//Implement strStr().
//
//Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
//
//Example 1:
//
//Input: haystack = "hello", needle = "ll"
//Output: 2
//Example 2:
//
//Input: haystack = "aaaaa", needle = "bba"
//Output: -1
//Clarification:
//
//What should we return when needle is an empty string? This is a great question to ask during an interview.
//
//For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C's strstr() and Java's indexOf().

func strStr(haystack string, needle string) int {
	if len(needle) == 0 {
		return 0
	}
	for i := 0; i < len(haystack)-len(needle)+1; i++ {
		var j int
		for j = 0; j < len(needle); j++ {
			if haystack[i+j] != needle[j] {
				break
			}
		}
		if j == len(needle) {
			return i
		}
	}
	return -1
}