feat: add javascript solution to lcci problem: No.08.03. Magic Index … (#386)

* feat: add javascript solution to lcci problem: No.08.03. Magic Index LCCI
* feat: add javascript solution to lcci problem: No.1863.Sum of All Subset XOR Totals

Author: zhaocchen

lcci/08.03.Magic Index/README.md

@@ -48,6 +48,27 @@
 
 ```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var findMagicIndex = function(nums) {
+    return helper(nums, 0, nums.length - 1);
+};
+
+function helper(nums, left, right) {
+    if (left > right) return -1;
+    let mid = Math.floor((left + right) / 2);
+    let leftIndex = helper(nums, left, mid - 1);
+    if (leftIndex != -1) return leftIndex;
+    if (nums[mid] == mid) return mid;
+    return helper(nums, mid + 1, right);
+}
+```
+
 ### **...**
 
 ```

lcci/08.03.Magic Index/README_EN.md

@@ -48,6 +48,27 @@
 
 ```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var findMagicIndex = function(nums) {
+    return helper(nums, 0, nums.length - 1);
+};
+
+function helper(nums, left, right) {
+    if (left > right) return -1;
+    let mid = Math.floor((left + right) / 2);
+    let leftIndex = helper(nums, left, mid - 1);
+    if (leftIndex != -1) return leftIndex;
+    if (nums[mid] == mid) return mid;
+    return helper(nums, mid + 1, right);
+}
+```
+
 ### **...**
 
 ```

lcci/08.03.Magic Index/Solution.js

@@ -0,0 +1,16 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+ var findMagicIndex = function(nums) {
+    return helper(nums, 0, nums.length - 1);
+};
+
+function helper(nums, left, right) {
+    if (left > right) return -1;
+    let mid = Math.floor((left + right) / 2);
+    let leftIndex = helper(nums, left, mid - 1);
+    if (leftIndex != -1) return leftIndex;
+    if (nums[mid] == mid) return mid;
+    return helper(nums, mid + 1, right);
+}

solution/1800-1899/1863.Sum of All Subset XOR Totals/README.md

@@ -87,6 +87,32 @@
 
 ```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+ var subsetXORSum = function(nums) {
+    let res = [];
+    let prev = 0;
+    dfs(nums, 0, prev, res);
+    return res.reduce((a, c) => a + c, 0)
+};
+
+function dfs(nums, depth, prev, res) {
+    res.push(prev);
+    for (let i = depth; i < nums.length; i++) {
+        prev ^= nums[i];
+        depth++;
+        dfs(nums, depth, prev, res);
+        // bracktrack
+        prev ^= nums[i];
+    }
+}
+```
+
 ### **...**
 
 ```

solution/1800-1899/1863.Sum of All Subset XOR Totals/README_EN.md

@@ -80,6 +80,32 @@
 
 ```
 
+### **JavaScript**
+
+```js
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+ var subsetXORSum = function(nums) {
+    let res = [];
+    let prev = 0;
+    dfs(nums, 0, prev, res);
+    return res.reduce((a, c) => a + c, 0)
+};
+
+function dfs(nums, depth, prev, res) {
+    res.push(prev);
+    for (let i = depth; i < nums.length; i++) {
+        prev ^= nums[i];
+        depth++;
+        dfs(nums, depth, prev, res);
+        // bracktrack
+        prev ^= nums[i];
+    }
+}
+```
+
 ### **...**
 
 ```

solution/1800-1899/1863.Sum of All Subset XOR Totals/Solution.js

@@ -0,0 +1,21 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+ var subsetXORSum = function(nums) {
+    let res = [];
+    let prev = 0;
+    dfs(nums, 0, prev, res);
+    return res.reduce((a, c) => a + c, 0)
+};
+
+function dfs(nums, depth, prev, res) {
+    res.push(prev);
+    for (let i = depth; i < nums.length; i++) {
+        prev ^= nums[i];
+        depth++;
+        dfs(nums, depth, prev, res);
+        // bracktrack
+        prev ^= nums[i];
+    }
+}