subtree-of-another-tree solution

Author: byol-han

subtree-of-another-tree/byol-han.js

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+/**
+ * https://leetcode.com/problems/subtree-of-another-tree/description/
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {TreeNode} subRoot
+ * @return {boolean}
+ */
+var isSubtree = function (root, subRoot) {
+  // If the main tree is empty, it can't contain subRoot
+  if (!root) return false;
+
+  // If the trees rooted at current node are the same, return true
+  if (isSameTree(root, subRoot)) {
+    return true;
+  }
+
+  // Otherwise, recursively check left and right subtrees
+  return isSubtree(root.left, subRoot) || isSubtree(root.right, subRoot);
+};
+
+function isSameTree(s, t) {
+  // If both nodes are null, trees are identical at this branch
+  if (!s && !t) return true;
+
+  // If only one is null, trees are not identical
+  if (!s || !t) return false;
+
+  // If current node values are different, trees are not identical
+  if (s.val !== t.val) return false;
+
+  // Recursively check left and right children
+  return isSameTree(s.left, t.left) && isSameTree(s.right, t.right);
+}