strStr算法实现

刷leetcode，一题花了不少次，总是会提示有错误的地方，最后看了c++的实现方法，也算是写了出来

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

/** * @param {string} haystack * @param {string} needle * @return {number} */var strStr = function(haystack, needle) {  if(needle.length==0) return 0;    if(needle.length>haystack.length) return -1;    index=0;    while(index+needle.length<=haystack.length){        for(i=0;i<=needle.length;){            if(i==needle.length) {                return index;            }            if(needle[i]!=haystack[i+index]){                index++;                break;            }            else if(needle[i]==haystack[i+index]){                i++;            }        }    }    return -1;};

做了这么多的算法题，感觉用到的for循环不是很多，而每次做题，本能第一反应都是用for，感觉需要有所改变了，也要更加完善自己的逻辑思维