update: 99

Author: hijiangtao

README.md

@@ -69,6 +69,7 @@ This is the solutions collection of my LeetCode submissions, most of them are pr
 | 96  | [unique-binary-search-trees](https://leetcode.com/problems/unique-binary-search-trees/)                                                         | [TypeScript](./src/unique-binary-search-trees/res.ts)                                                                 | Medium     |
 | 97  | [interleaving-string](https://leetcode.com/problems/interleaving-string/)                                                                       | [TypeScript](./src/interleaving-string/res.ts)                                                                        | Medium     |
 | 98  | [Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/)                                                       | [JavaScript](./src/validate-binary-search-tree/res.js)                                                                | Medium     |
+| 99  | [recover-binary-search-tree](https://leetcode.com/problems/recover-binary-search-tree/)                                                         | [TypeScript](./src/recover-binary-search-tree/res.ts)                                                                 | Medium     |
 | 100 | [Same Tree](https://leetcode.com/problems/same-tree/)                                                                                           | [JavaScript](./src/same-tree/res.js)                                                                                  | Easy       |
 | 101 | [Symmetric Tree](https://leetcode.com/problems/symmetric-tree/)                                                                                 | [JavaScript](./src/symmetric-tree/res.js)                                                                             | Easy       |
 | 102 | [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/)                                           | [JavaScript](./src/binary-tree-level-order-traversal/res.js)                                                          | Medium     |

src/recover-binary-search-tree/res.ts

@@ -0,0 +1,65 @@
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+const inorder = (root: TreeNode | null, nums: number[]) => {
+    if (!root) {
+        return ;
+    }
+
+    inorder(root.left, nums);
+    nums.push(root.val);
+    inorder(root.right, nums);
+}
+
+const findSwapTwoNums = (root: TreeNode | null, nums: number[]) => {
+    let x = -1, y = -1;
+    for (let i = 1; i < nums.length; i++) {
+        if (nums[i] < nums[i-1]) {
+            y = i;
+
+            if (x === -1) {
+                x = i-1;
+            } else {
+                break;
+            }
+        }
+    }
+
+    return [nums[x], nums[y]];
+}
+
+const recover = (root: TreeNode | null, index: number, x: number, y: number) => {
+    if (!root || index === 0) {
+        return ;
+    }
+
+    if ([x, y].includes(root.val)) {
+        root.val = root.val === x ? y : x;
+        index--;
+    }
+
+    recover(root.left, index, x, y);
+    recover(root.right, index, x, y);
+}
+
+/**
+ Do not return anything, modify root in-place instead.
+ */
+function recoverTree(root: TreeNode | null): void {
+    const nums: number[] = [];
+
+    inorder(root, nums);
+    const [x, y] = findSwapTwoNums(root, nums);
+    recover(root, 2, x, y);
+};