implement.js

// 28. Implement strStr()

// Implement strStr().

// Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

// 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().

 

// Example 1:

// Input: haystack = "hello", needle = "ll"
// Output: 2
// Example 2:

// Input: haystack = "aaaaa", needle = "bba"
// Output: -1

var strStr = function(haystack, needle) {
    if(needle == ""){
        return 0
    }
    if(!needle || !haystack){
        return -1
    }
    for(let i = 0; i< haystack.length; i++){
        let temp = haystack.slice(i, needle.length+i)
        if(needle === temp){
            return i
        }
    }
    return -1
};