Feat: 100. Same Tree

Author: HC-kang

same-tree/HC-kang.ts

@@ -0,0 +1,41 @@
+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/same-tree/description/
+ * T.C. O(n)
+ * S.C. O(n)
+ */
+function isSameTree(p: TreeNode | null, q: TreeNode | null): boolean {
+  if (p === null && q === null) return true;
+  if (p === null || q === null) return false;
+  if (p.val !== q.val) return false;
+  return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
+}
+
+/**
+ * T.C. O(n)
+ * S.C. O(n)
+ */
+function isSameTree(p: TreeNode | null, q: TreeNode | null): boolean {
+  const stack: [TreeNode | null, TreeNode | null][] = [[p, q]];
+
+  while (stack.length) {
+    const [node1, node2] = stack.pop()!;
+    if (node1 === null && node2 === null) continue;
+    if (node1 === null || node2 === null) return false;
+    if (node1.val !== node2.val) return false;
+    stack.push([node1.left, node2.left]);
+    stack.push([node1.right, node2.right]);
+  }
+
+  return true;
+}