3902. Zigzag Level Sum of Binary Tree

MediumTree Preparing judge… LeetCode

TreeBreadth-First SearchBinary Tree

Hint 1

Use level-order traversal (BFS) to process the tree level by level

Hint 2

Maintain a list (or queue) of nodes for the current level

Hint 3

Alternate traversal direction using a flag (odd level vs even level)

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Input