Feat: 572. Subtree of Another Tree

Author: HC-kang

subtree-of-another-tree/HC-kang.ts

@@ -0,0 +1,28 @@
+// 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;
+//   }
+// }
+
+/**
+ * https://leetcode.com/problems/subtree-of-another-tree
+ * T.C. O(n * m)
+ * S.C. O(n)
+ */
+function isSubtree(root: TreeNode | null, subRoot: TreeNode | null): boolean {
+  if (!root) return false;
+  if (isSameTree(root, subRoot)) return true;
+  return isSubtree(root.left, subRoot) || isSubtree(root.right, subRoot);
+}
+
+function isSameTree(p: TreeNode | null, q: TreeNode | null): boolean {
+  if (!p && !q) return true;
+  if (!p || !q) return false;
+  if (p.val !== q.val) return false;
+  return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
+}