update: 28

Author: hijiangtao

README.md

@@ -26,6 +26,7 @@ This is the solutions collection of my LeetCode submissions, most of them are pr
 |22|[Generate Parentheses](https://leetcode.com/problems/generate-parentheses/) | [JavaScript](./src/generate-parentheses/res.js)|Medium|
 |26|[Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/) | [JavaScript](./src/remove-duplicates-from-sorted-array/res.js)|Easy|
 |27|[Remove Element](https://leetcode.com/problems/remove-element/) | [JavaScript](./src/remove-element/res.js)|Easy|
+|28|[Implement strStr()](https://leetcode.com/problems/implement-strstr/) | [JavaScript](./src/implement-strstr/res.js)|Easy|
 |29|[Divide Two Integers](https://leetcode.com/problems/divide-two-integers/) | [JavaScript](./src/divide-two-integers/res.js)|Medium|
 |33|[Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/) | [JavaScript](./src/search-in-rotated-sorted-array/res.js)|Medium|
 |34|[Search for a Range](https://leetcode.com/problems/search-for-a-range/) | [JavaScript](./src/search-for-a-range/res.js)|Medium|

src/implement-strstr/res.js

@@ -0,0 +1,36 @@
+/**
+* KMP
+* @param {string} haystack
+* @param {string} needle
+* @return {number}
+*/
+var strStr = function(haystack, needle) {
+const hlen = haystack.length;
+const nlen = needle.length;
+if (!nlen) return 0;
+if (!hlen) return -1;
+
+let FSM = new Array(nlen);
+let X = 0, match = 0;
+for (let i = 0; i < nlen; i++) {
+match = needle[i].charCodeAt();
+FSM[i] = new Array(256);
+for (let j = 0; j < 256; j++) {
+FSM[i][j] = FSM[X][j] || 0;
+}
+
+FSM[i][match] = i + 1;
+if (i > 0) {
+X = FSM[X][match];
+}
+}
+
+let state = 0;
+for (let i = 0; i < hlen; i++) {
+state = FSM[state][haystack[i].charCodeAt()];
+if (state === nlen) {
+return i - nlen + 1;
+}
+}
+return -1;
+};