#leetcode 28 Implement strStr() 子串查找

嗯...爲了找工做&提升編程能力,從今天要開始繼續作算法題了,一天一道吧!
第一天,偷個懶,作個簡單的題目.

題目

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

思路

-暴力解法: 就是從頭開始遍歷haystack, 而後每一個都和needle匹配一次,假如匹配到needle的最後一個index,那就是成功了.返回i(開始的序號)不然返回-1

解法(暴力破解)明天更新kmp算法版

var strStr = function(haystack, needle) {
     for (let i=0; i <= haystack.length - needle.length; i++){
        var flag=true;
        for (let j=0; j < needle.length; j++){
            if(haystack[i+j] != needle[j]){
                flag=false;
                break;
            }
        }
         
        if(flag)
            return i;
        }
    
        return -1;
};