0662-maximum-width-of-binary-tree.java

class Solution {

    public int widthOfBinaryTree(TreeNode root) {
        Queue<Pair<TreeNode, Integer>> q = new LinkedList<>();
        int maxWidth = 0;
        q.offer(new Pair(root, 1));
        while (!q.isEmpty()) {
            int l = q.peek().getValue();
            int r = l;
            int size = q.size();
            for (int i = 0; i < size; i++) {
                TreeNode cur = q.peek().getKey();
                r = q.poll().getValue();
                if (cur.left != null) q.offer(new Pair(cur.left, 2 * r));
                if (cur.right != null) q.offer(new Pair(cur.right, 2 * r + 1));
            }
            maxWidth = Math.max(maxWidth, r - l + 1);
        }
        return maxWidth;
    }
}