feat: Add solution for delete-leaves-with-a-given-value problem

Author: pragusga25

medium/delete-leaves-with-a-given-value.test.ts

@@ -0,0 +1,91 @@
+// Problem: https://leetcode.com/problems/delete-leaves-with-a-given-value/
+// Doc: https://leetcode.com/problems/delete-leaves-with-a-given-value/solutions/5504665/efficient-leaf-node-removal-in-a-binary-tree/
+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;
+  }
+}
+
+function removeLeafNodes(
+  root: TreeNode | null,
+  target: number
+): TreeNode | null {
+  if (!root) return root;
+  root.left = removeLeafNodes(root.left, target);
+  root.right = removeLeafNodes(root.right, target);
+
+  if (root.val === target && !root.left && !root.right) {
+    root = null;
+  }
+
+  return root;
+}
+
+const getValues = (root: TreeNode | null): (number | null)[] => {
+  if (!root) return [null];
+
+  return [root.val, ...getValues(root.left), ...getValues(root.right)];
+};
+
+describe('Delete Leaves With a Given Value', () => {
+  it('#1 should remove leaf nodes with value 3', () => {
+    const root = new TreeNode(
+      1,
+      new TreeNode(2, new TreeNode(2), null),
+      new TreeNode(3, new TreeNode(2), new TreeNode(4))
+    );
+    const target = 3;
+
+    const result = removeLeafNodes(root, target);
+
+    const actual = getValues(result);
+    const expected = getValues(
+      new TreeNode(
+        1,
+        new TreeNode(2, new TreeNode(2), null),
+        new TreeNode(3, new TreeNode(2), new TreeNode(4))
+      )
+    );
+
+    expect(actual).toEqual(expected);
+  });
+
+  it('#2 should remove leaf nodes with value 1', () => {
+    const root = new TreeNode(1, new TreeNode(1), new TreeNode(1));
+    const target = 1;
+
+    const result = removeLeafNodes(root, target);
+
+    const actual = getValues(result);
+    const expected = getValues(null);
+
+    expect(actual).toEqual(expected);
+  });
+
+  it('#3 should remove leaf nodes with value 1', () => {
+    const root = new TreeNode(
+      1,
+      new TreeNode(2, new TreeNode(2), null),
+      new TreeNode(1, new TreeNode(2), new TreeNode(1))
+    );
+    const target = 1;
+
+    const result = removeLeafNodes(root, target);
+
+    const actual = getValues(result);
+    const expected = getValues(
+      new TreeNode(
+        1,
+        new TreeNode(2, new TreeNode(2), null),
+        new TreeNode(1, new TreeNode(2), null)
+      )
+    );
+
+    expect(actual).toEqual(expected);
+  });
+});