Question 40 of 75 - LeetCode Weekly Challenge

LeetCode Challenge #1161. Maximum Level Sum of a Binary Tree

Given the root of a binary tree, the level of its root is 1, the level of its children is 2, and so on.

Return the smallest level x such that the sum of all the values of nodes at level x is maximal.

 

Example 1:

capture

Input: root = [1,7,0,7,-8,null,null]
Output: 2
Explanation: 
Level 1 sum = 1.
Level 2 sum = 7 + 0 = 7.
Level 3 sum = 7 + -8 = -1.
So we return the level with the maximum sum which is level 2.

Example 2:

Input: root = [989,null,10250,98693,-89388,null,null,null,-32127]
Output: 2

 

Constraints:

  • The number of nodes in the tree is in the range [1, 104].
  • -105 <= Node.val <= 105
Video Solution
C++ Solution
				
					class Solution {
public:
    int bfs(TreeNode* root)
    {
       queue<TreeNode*> q;
        
        int n,sum=0,level=1,maxm=INT_MIN,maxLevel;
        q.push(root);
        while(!q.empty()){
            n = q.size();
            sum = 0;
            while(n--){
                TreeNode* node = q.front();q.pop();
                sum += node->val;
                if(node->left)q.push(node->left);
                if(node->right)q.push(node->right);
            }
            if(sum>maxm){
                maxm = sum;
                maxLevel = level;
            }
            level++;
        }
        return maxLevel;
    }
    
    int maxLevelSum(TreeNode* root) {

        return bfs(root);
        
    }
};
				
			

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