194th Commit

README.md

@@ -169,17 +169,18 @@ Ace Coding Interview with 75 Qs
 [206]: ./src/page-2/206.%20Reverse%20Linked%20List/reverseList.ts
 [2130]: ./src/page-20/2130.%20Maximum%20Twin%20Sum%20of%20a%20Linked%20List/pairSum.ts
 
-| Binary Tree - DFS                            |                 |        |
-| -------------------------------------------- | --------------- | ------ |
-| 104. Maximum Depth of Binary Tree            | [Solution][104] | Easy   |
-| 872. Leaf-Similar Trees                      | [Solution][872] | Easy   |
-| 1448. Count Good Nodes in Binary Tree        | Solution        | Medium |
-| 437. Path Sum III                            | Solution        | Medium |
-| 1372. Longest ZigZag Path in a Binary Tree   | Solution        | Medium |
-| 236. Lowest Common Ancestor of a Binary Tree | Solution        | Medium |
+| Binary Tree - DFS                            |                  |        |
+| -------------------------------------------- | ---------------- | ------ |
+| 104. Maximum Depth of Binary Tree            | [Solution][104]  | Easy   |
+| 872. Leaf-Similar Trees                      | [Solution][872]  | Easy   |
+| 1448. Count Good Nodes in Binary Tree        | [Solution][1448] | Medium |
+| 437. Path Sum III                            | Solution         | Medium |
+| 1372. Longest ZigZag Path in a Binary Tree   | Solution         | Medium |
+| 236. Lowest Common Ancestor of a Binary Tree | Solution         | Medium |
 
 [104]: ./src/page-2/104.%20Maximum%20Depth%20of%20Binary%20Tree/maxDepth.ts
 [872]: ./src/page-9/872.%20Leaf-Similar%20Trees/leafSimilar.ts
+[1448]: ./src/page-14/1448.%20Count%20Good%20Nodes%20in%20Binary%20Tree/goodNodes.ts
 
 | Binary Tree - BFS                        |          |        |
 | ---------------------------------------- | -------- | ------ |

src/page-14/1448. Count Good Nodes in Binary Tree/goodNodes.test.ts

@@ -0,0 +1,22 @@
+import { generateBinaryTree } from '~/utils/binary-tree';
+
+import { goodNodes } from './goodNodes';
+
+describe('1448. Count Good Nodes in Binary Tree', () => {
+  test('goodNodes', () => {
+    {
+      const root = generateBinaryTree([3, 1, 4, 3, null, 1, 5]);
+      expect(goodNodes(root)).toBe(4);
+    }
+
+    {
+      const root = generateBinaryTree([3, 3, null, 4, 2]);
+      expect(goodNodes(root)).toBe(3);
+    }
+
+    {
+      const root = generateBinaryTree([1]);
+      expect(goodNodes(root)).toBe(1);
+    }
+  });
+});

src/page-14/1448. Count Good Nodes in Binary Tree/goodNodes.ts

@@ -0,0 +1,29 @@
+import type { TreeNode } from '~/utils/binary-tree';
+
+type GoodNodes = (root: TreeNode | null) => number;
+
+/**
+ * Accepted
+ */
+export const goodNodes: GoodNodes = (root) => {
+  // Helper function to perform DFS
+  function dfs(node: TreeNode | null, maxVal: number): number {
+    if (node === null) return 0;
+
+    // Determine if the current node is a "good" node
+    let count = 0;
+    if (node.val >= maxVal) count = 1;
+
+    // Update maxVal for the next recursion
+    const newMaxVal = Math.max(maxVal, node.val);
+
+    // Continue DFS on left and right children
+    count += dfs(node.left, newMaxVal);
+    count += dfs(node.right, newMaxVal);
+
+    return count;
+  }
+
+  // Start DFS with the root node
+  return dfs(root, root?.val ?? Number.NEGATIVE_INFINITY);
+};