subtree of another tree solution

Author: hyer0705

subtree-of-another-tree/hyer0705.ts

@@ -0,0 +1,31 @@
+/**
+ * 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)
+ *     }
+ * }
+ */
+
+function isSubtree(root: TreeNode | null, subRoot: TreeNode | null): boolean {
+  if (!root) return false;
+
+  const isSameTree = (root: TreeNode | null, subRoot: TreeNode | null): boolean => {
+    if (!root && !subRoot) return true;
+    if (!root || !subRoot) return false;
+    if (root.val !== subRoot.val) return false;
+
+    return isSameTree(root.left, subRoot.left) && isSameTree(root.right, subRoot.right);
+  };
+
+  const current = isSameTree(root, subRoot);
+  const left = isSubtree(root.left, subRoot);
+  const right = isSubtree(root.right, subRoot);
+
+  return current || left || right;
+}