P120.java

import java.util.*;
import java.io.*;

/************************************************************
 * 
 * Following is the TreeNode class structure
 * 
 * class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * 
 * TreeNode(int val) {
 * this.val = val;
 * this.left = null;
 * this.right = null;
 * }
 * }
 * 
 * 
 ************************************************************/

public class P120 {
    public static int getMaxWidth(TreeNode root) {
        if (root == null)
            return 0;
        Queue<TreeNode> q = new LinkedList<>();
        q.add(root);
        int ans = 0;
        while (!q.isEmpty()) {
            int size = q.size();
            ans = Math.max(ans, size);
            for (int i = 0; i < size; i++) {
                TreeNode curr = q.poll();
                if (curr.left != null)
                    q.add(curr.left);
                if (curr.right != null)
                    q.add(curr.right);
            }
        }
        return ans;
    }
}