Maximum Width of Binary Tree LeetCode Solution

Here, We see Maximum Width of Binary Tree LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.

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Maximum Width of Binary Tree LeetCode Solution

Maximum Width of Binary Tree LeetCode Solution

Problem Statement

Given the root of a binary tree, return the maximum width of the given tree.

The maximum width of a tree is the maximum width among all levels.

The width of one level is defined as the length between the end-nodes (the leftmost and rightmost non-null nodes), where the null nodes between the end-nodes that would be present in a complete binary tree extending down to that level are also counted into the length calculation.

It is guaranteed that the answer will in the range of a 32-bit signed integer.

Example 1:

width1 tree

Input: root = [1,3,2,5,3,null,9]
Output: 4
Explanation: The maximum width exists in the third level with length 4 (5,3,null,9).

Example 2:

maximum width of binary tree v3

Input: root = [1,3,2,5,null,null,9,6,null,7]
Output: 7
Explanation: The maximum width exists in the fourth level with length 7 (6,null,null,null,null,null,7).

Example 3:

width3 tree

Input: root = [1,3,2,5]
Output: 2
Explanation: The maximum width exists in the second level with length 2 (3,2).

Maximum Width of Binary Tree LeetCode Solution C++

class Solution {
public:
    int widthOfBinaryTree(TreeNode* root) {
        if (root == NULL) return 0;
        int max_width = 1;
        queue<pair<TreeNode*, int>> q;
        q.push({root, 0});
        while (!q.empty()) {
            int level_size = q.size();
            int start_index = q.front().second;
            int end_index = q.back().second;
            max_width = max(max_width, end_index - start_index + 1);
            for (int i = 0; i < level_size; ++i) {
                auto node_index_pair = q.front();
                TreeNode* node = node_index_pair.first;
                int node_index = node_index_pair.second - start_index;
                q.pop();
                if (node->left != nullptr) {
                    q.push({node->left, 2LL * node_index + 1});
                }
                if (node->right != nullptr) {
                    q.push({node->right, 2LL * node_index + 2});
                }
            }
        }
        return max_width;
    }
};Code language: PHP (php)

Maximum Width of Binary Tree LeetCode Solution Java

class Solution {
    public int widthOfBinaryTree(TreeNode root) {
        if (root == null) return 0;
        Queue<Pair<TreeNode, Integer>> queue = new LinkedList<>();
        queue.add(new Pair<>(root, 0));
        int maxWidth = 0;
        while (!queue.isEmpty()) {
            int levelLength = queue.size();
            int levelStart = queue.peek().getValue();
            int index = 0; 
            for (int i = 0; i < levelLength; i++) {
                Pair<TreeNode, Integer> pair = queue.poll();
                TreeNode node = pair.getKey();
                index = pair.getValue();
                if (node.left != null) {
                    queue.add(new Pair<>(node.left, 2*index));
                }
                if (node.right != null) {
                    queue.add(new Pair<>(node.right, 2*index+1));
                }
            }
            maxWidth = Math.max(maxWidth, index - levelStart + 1);
        }
        return maxWidth;
    }
}Code language: JavaScript (javascript)

Maximum Width of Binary Tree Solution JavaScript

var widthOfBinaryTree = function(root) {
    const minPos = [0];
    let maxWidth = 0;
    callDFS(root, 0, 0);
    return maxWidth;
    function callDFS(node, level, pos) {
        if(!node) return;
        if(minPos[level] === undefined) minPos.push(pos);
        const diff = pos - minPos[level];
        maxWidth = Math.max(maxWidth, diff+1);
        callDFS(node.left, level+1, diff*2);
        callDFS(node.right, level+1, diff*2+1);
    }
};Code language: JavaScript (javascript)

Maximum Width of Binary Tree Solution Python

class Solution(object):
    def widthOfBinaryTree(self, root):
        if not root:
            return 0
        queue = deque([(root, 0)])
        max_width = 0
        while queue:
            level_length = len(queue)
            _, level_start = queue[0]
            for i in range(level_length):
                node, index = queue.popleft()
                if node.left:
                    queue.append((node.left, 2*index))
                if node.right:
                    queue.append((node.right, 2*index+1))    
            max_width = max(max_width, index - level_start + 1)
        return max_width
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