Skip to main content

5. Same Tree

easyAsked at Flipkart

Check whether two binary trees are structurally identical with equal node values — Flipkart uses it to test recursion fluency before diving into category-tree problems.

By Alex Chen, Founder, InterviewChamp.AI · Last verified

Problem

Given the roots of two binary trees p and q, return true if they are the same tree. Two trees are the same when they are structurally identical and the nodes have the same value.

Constraints

  • 0 <= nodes <= 100
  • -10^4 <= Node.val <= 10^4

Examples

Example 1

Input
p = [1,2,3], q = [1,2,3]
Output
true

Example 2

Input
p = [1,2], q = [1,null,2]
Output
false

Approaches

1. Brute force serialize

Serialize both trees with null markers and compare strings.

Time
O(n)
Space
O(n)
const s = (n) => n ? `${n.val},${s(n.left)},${s(n.right)}` : '#';
return s(p) === s(q);

Tradeoff:

2. Parallel DFS

Walk both trees in lockstep; short-circuit on the first mismatch. Avoids the overhead of building strings.

Time
O(n)
Space
O(h)
function isSameTree(p, q) {
  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);
}

Tradeoff:

Flipkart-specific tips

Flipkart interviewers map this to comparing two snapshots of their category catalog tree — call out null-vs-empty handling and they will mentally tick the box.

Solve it now

Free. No sign-up. Python and JavaScript run instantly in your browser.

Output

Press Run or Cmd+Enter to execute

Practice these live with InterviewChamp.AI

Drill Same Tree and other Flipkart interview questions under real-loop conditions with instant feedback on your reasoning, complexity claims, and code.

Practice these live with InterviewChamp.AI →