feat: add js solution to lc problem: No. 2096

Author: rain84

solution/2000-2099/2096.Step-By-Step Directions From a Binary Tree Node to Another/README.md

@@ -345,6 +345,62 @@ function getDirections(root: TreeNode | null, startValue: number, destValue: num
 }
 ```
 
+#### JavaScript
+
+```js
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {number} startValue
+ * @param {number} destValue
+ * @return {string}
+ */
+var getDirections = function (root, startValue, destValue) {
+    const lca = (node, p, q) => {
+        if (node === null || [p, q].includes(node.val)) {
+            return node;
+        }
+        const left = lca(node.left, p, q);
+        const right = lca(node.right, p, q);
+
+        return left && right ? node : left ?? right;
+    };
+
+    const dfs = (node, x, path) => {
+        if (node === null) {
+            return false;
+        }
+        if (node.val === x) {
+            return true;
+        }
+        path.push('L');
+        if (dfs(node.left, x, path)) {
+            return true;
+        }
+        path[path.length - 1] = 'R';
+        if (dfs(node.right, x, path)) {
+            return true;
+        }
+        path.pop();
+        return false;
+    };
+
+    const node = lca(root, startValue, destValue);
+    const pathToStart = [];
+    const pathToDest = [];
+    dfs(node, startValue, pathToStart);
+    dfs(node, destValue, pathToDest);
+    return 'U'.repeat(pathToStart.length) + pathToDest.join('');
+};
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

solution/2000-2099/2096.Step-By-Step Directions From a Binary Tree Node to Another/README_EN.md

@@ -341,6 +341,62 @@ function getDirections(root: TreeNode | null, startValue: number, destValue: num
 }
 ```
 
+#### JavaScript
+
+```js
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {number} startValue
+ * @param {number} destValue
+ * @return {string}
+ */
+var getDirections = function (root, startValue, destValue) {
+    const lca = (node, p, q) => {
+        if (node === null || [p, q].includes(node.val)) {
+            return node;
+        }
+        const left = lca(node.left, p, q);
+        const right = lca(node.right, p, q);
+
+        return left && right ? node : left ?? right;
+    };
+
+    const dfs = (node, x, path) => {
+        if (node === null) {
+            return false;
+        }
+        if (node.val === x) {
+            return true;
+        }
+        path.push('L');
+        if (dfs(node.left, x, path)) {
+            return true;
+        }
+        path[path.length - 1] = 'R';
+        if (dfs(node.right, x, path)) {
+            return true;
+        }
+        path.pop();
+        return false;
+    };
+
+    const node = lca(root, startValue, destValue);
+    const pathToStart = [];
+    const pathToDest = [];
+    dfs(node, startValue, pathToStart);
+    dfs(node, destValue, pathToDest);
+    return 'U'.repeat(pathToStart.length) + pathToDest.join('');
+};
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

solution/2000-2099/2096.Step-By-Step Directions From a Binary Tree Node to Another/Solution.js

@@ -0,0 +1,51 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {number} startValue
+ * @param {number} destValue
+ * @return {string}
+ */
+var getDirections = function (root, startValue, destValue) {
+    const lca = (node, p, q) => {
+        if (node === null || [p, q].includes(node.val)) {
+            return node;
+        }
+        const left = lca(node.left, p, q);
+        const right = lca(node.right, p, q);
+
+        return left && right ? node : left ?? right;
+    };
+
+    const dfs = (node, x, path) => {
+        if (node === null) {
+            return false;
+        }
+        if (node.val === x) {
+            return true;
+        }
+        path.push('L');
+        if (dfs(node.left, x, path)) {
+            return true;
+        }
+        path[path.length - 1] = 'R';
+        if (dfs(node.right, x, path)) {
+            return true;
+        }
+        path.pop();
+        return false;
+    };
+
+    const node = lca(root, startValue, destValue);
+    const pathToStart = [];
+    const pathToDest = [];
+    dfs(node, startValue, pathToStart);
+    dfs(node, destValue, pathToDest);
+    return 'U'.repeat(pathToStart.length) + pathToDest.join('');
+};