Diameter of Binary Tree

LeetCode 543 • Easy • Trees

Longest path between any two nodes. At each node: diameter = left_depth + right_depth. DFS returns depth; track max diameter globally.

TimeO(n)

SpaceO(h)

node: — diameter: —

Current

Depth

node —

left —

right —

diameter —

Speed:

Ready

Press Play. DFS post-order: at each node, diameter = left+right, return 1+max(left,right).

Whiteboard

Size:3

Type It

Practice until you don't need to look. Diameter = left_depth + right_depth at each node.

═══ DIAMETER OF BINARY TREE — DFS ═══

PATTERN ▸ DFS with diameter tracking O(n) · O(h)

① INIT

diameter = 0 (global or nonlocal)

② DEPTH HELPER

def depth(node): if not node: return 0

left, right = depth(left), depth(right)

diameter = max(diameter, left+right)

return 1 + max(left, right)

③ RETURN

return diameter

your implementation

Verify: