week14: add three js solution

Author: swiftwind0405

README.md

@@ -281,7 +281,7 @@
 |163|[Missing Ranges](https://leetcode.com/problems/missing-ranges/) ♥ | |Medium|
 |162|[Find Peak Element](https://leetcode.com/problems/find-peak-element/) | |Medium|
 |161|[One Edit Distance](https://leetcode.com/problems/one-edit-distance/)♥ | |Medium|
-|160|[Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists/) | [java](./algorithms/intersectionOfTwoLinkedLists/Solution.java)  |Easy|
+|160|[Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists/) | [java](./algorithms/intersectionOfTwoLinkedLists/Solution.java), [js](./algorithms/intersectionOfTwoLinkedLists/Solution.js)  |Easy|
 |159|[Longest Substring with At Most Two Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters/) ♥ | |Hard|
 |158|[Read N Characters Given Read4 II - Call multiple times](https://leetcode.com/problems/read-n-characters-given-read4-ii-call-multiple-times/) ♥ | |Hard|
 |157|[Read N Characters Given Read4](https://leetcode.com/problems/read-n-characters-given-read4/) ♥ | |Easy|
@@ -363,7 +363,7 @@
 |81|[Search in Rotated Sorted Array II](https://leetcode.com/problems/search-in-rotated-sorted-array-ii/)| |Medium|
 |80|[Remove Duplicates from Sorted Array II](https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/)| |Medium|
 |79|[Word Search](https://leetcode.com/problems/word-search/)| |Medium|
-|78|[Subsets](https://leetcode.com/problems/subsets/)| |Medium|
+|78|[Subsets](https://leetcode.com/problems/subsets/)| [js](./algorithms/subsets/Solution.js) |Medium|
 |77|[Combinations](https://leetcode.com/problems/combinations/)| |Medium|
 |76|[Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/)| |Hard|
 |75|[Sort Colors](https://leetcode.com/problems/sort-colors/)| |Medium|
@@ -395,7 +395,7 @@
 |49|[Group Anagrams](https://leetcode.com/problems/anagrams/)| |Medium|
 |48|[Rotate Image](https://leetcode.com/problems/rotate-image/)| |Medium|
 |47|[Permutations II](https://leetcode.com/problems/permutations-ii/)| |Hard|
-|46|[Permutations](https://leetcode.com/problems/permutations/)| |Medium|
+|46|[Permutations](https://leetcode.com/problems/permutations/)| [js](./algorithms/permutations/Solution.js) |Medium|
 |45|[Jump Game II](https://leetcode.com/problems/jump-game-ii/)| |Hard|
 |44|[Wildcard Matching](https://leetcode.com/problems/wildcard-matching/)| |Hard|
 |43|[Multiply Strings](https://leetcode.com/problems/multiply-strings/)| |Medium|

algorithms/intersectionOfTwoLinkedLists/Solution.js

@@ -0,0 +1,14 @@
+var getIntersectionNode = function(headA, headB) {
+    if (!headA || !headB) return null;
+
+    let pA = headA,
+        pB = headB;
+    // 相等只有2种情况：
+    // 1. 两者相交 2. 都走到了最后
+    while (pA !== pB) {
+        // 如果没走到最后，就往后走一步；否则就指向互相的头节点
+        pA = pA === null ? headB : pA.next;
+        pB = pB === null ? headA : pB.next;
+    }
+    return pA;
+};

algorithms/permutations/Solution.js

@@ -0,0 +1,19 @@
+var permute = function (nums) {
+    const res = [];
+    const backtrack = (path) => {
+        // 3. 递归的终点
+        if(path.length === nums.length) {
+            res.push(path);
+            return;
+        }
+        // 遍历所有数字
+        nums.forEach(n => {
+            // 2. 如果包含当前数字，也就是重复了，即死路，就不要递归了
+            if (path.includes(n)) return;
+            // 1. 把数字加到数组里，进行递归调用
+            backtrack(path.concat(n));
+        })
+    };
+    backtrack([]);
+    return res;
+};

algorithms/subsets/Solution.js

@@ -0,0 +1,20 @@
+var subsets = function (nums) {
+    const res = [];
+    const backtrack = (path, l, start) => {
+        if (path.length === l) {
+            res.push(path);
+            return;
+        }
+        // for循环遍历数组中的所有数字
+        // 没有用forEach来遍历是因为要保证子集的有序性，后面接的数字必须是当前数字后面的数字
+        // 因此还需要记录一个下标来
+        for (let i = start; i < nums.length; i++) {
+            backtrack(path.concat(nums[i]), l, i + 1);
+        }
+    };
+    // 在for循环中进行回溯的调用
+    for (let i = 0; i <= nums.length; i++) {
+        backtrack([], i, 0);
+    }
+    return res;
+};