← Tree Traversal

Micro-Drill #59 — Count nodes

Tree Traversal Target: 10s

Recursive node counting teaches divide-and-conquer tree thinking.

def count(node):
    if not node: return 0
    return 1 + count(node.left) + count(node.right)

Type it from memory. Go.

Practice Problems

• 222. Count Complete Tree Nodes
• 104. Maximum Depth of Binary Tree

Related Coding Drills

• Drill #141 — Count Good Nodes in Binary Tree Medium
• Drill #45 — Count connected components Easy
• Drill #83 — Count set bits Easy