28. Implement strStr()(js)
28. Implement 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
题意:实现一个函数strStr(),接收两个参数,haystack中是否存在needle子串,存在则返回needle首字符在haystack中的索引,不存在则返回-1
代码如下:
/** * @param {string} haystack * @param {string} needle * @return {number} */ var strStr = function(haystack, needle) { let hLen=haystack.length; let nLen=needle.length; let str=''; for(var i=0;i<=hLen-nLen;i++){ str=haystack.slice(i,nLen+i); if( str === needle) return i; } return -1 };