Implement strStr()

Author: w2xi

README.md

@@ -8,6 +8,7 @@
 |9|[回文数](https://leetcode-cn.com/problems/palindrome-number/)|[JavaScript](./algorithms/palindrome-number.js)|Easy|
 |14|[最长公共前缀](https://leetcode-cn.com/problems/longest-common-prefix/)|[JavaScript](./algorithms/longest-common-prefix.js)|Easy|
 |21|[合并两个有序链表](https://leetcode-cn.com/problems/merge-two-sorted-lists/)|[JavaScript](./algorithms/merge-two-sorted-lists.js)|Easy|
+|28|[实现 strStr()](https://leetcode-cn.com/problems/implement-strstr/)|[JavaScript](./algorithms/implement-strstr.js)|Easy|
 |66|[加一](https://leetcode-cn.com/problems/plus-one/)|[JavaScript](./algorithms/plus-one.js)|Easy|
 |136|[只出现一次的数字](https://leetcode-cn.com/problems/single-number/)|[JavaScript](./algorithms/single-number.js)|Easy|
 |189|[轮转数组](https://leetcode-cn.com/problems/rotate-array/)|[JavaScript](./algorithms/rotate-array.js)|Medium|

algorithms/implement-strstr.js

@@ -0,0 +1,24 @@
+// 暴力破解
+
+/**
+ * 实现 strStr()
+ * @param {string} haystack
+ * @param {string} needle
+ * @return {number}
+ */
+ var strStr = function(haystack, needle) {
+  if (!needle) {
+      return 0
+  }
+
+  for (let i = 0; i < haystack.length; i++) {
+      if (haystack.slice(i, i + needle.length) === needle ) {
+          return i
+      }
+  }
+
+  return -1
+};
+
+// KMP
+// 以后补充