Pattern visualizer

Maximum Depth of a Binary Tree

Depth is defined in terms of itself: a node's depth is 1 plus the deeper of its two children. That makes recursion the natural fit — each call waits on its children, and the answer climbs back up the call stack. Animated on: Return the number of nodes along the longest path from the root down to the farthest leaf, for the tree [3, 9, 20, null, null, 15, 7]..

Binary Trees

step 1 / 12

Call stack

maxDepth(3)

line 1

Call maxDepth(3). To answer for the root we first need the depths of its two children — so we go down before we can come back up.

Pseudocode

1FUNCTION maxDepth(node):
2  IF node is null:  RETURN 0
3  left = maxDepth(node.left)
4  right = maxDepth(node.right)
5  RETURN 1 + the larger of left and right
6END FUNCTION

← / → step · space play · Home restart

Where to practice Binary Trees

Practice Binary Trees problems All Binary Trees problems Back to roadmap