Find Sum of the Deepest Nodes in C++

Suppose we have a binary tree; we have to find the sum of values of its deepest leaves. So if the tree is like −

Then the output will be 11.

To solve this, we will follow these steps −

• Define a map m, and maxDepth

• Define a recursive method solve(), this will take node and level, initially level is 0

• if node is not present, then return

• maxDepth := max of level and maxDepth

• increase m[level] by value of node

• solve(left of node, level + 1)

• solve(right of node, level + 1)

• In the main method, setup maxDepth := 0, then solve(root, 0)

• return m[maxDepth]

Let us see the following implementation to get better understanding −

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
class TreeNode{
   public:
   int val;
   TreeNode *left, *right;
   TreeNode(int data){
      val = data;
      left = NULL;
      right = NULL;
   }
};
class Solution {
   public:
   int maxDepth;
   map <int, int> m;
   void solve(TreeNode* node, int level = 0){
      if(!node)return;
      maxDepth = max(level, maxDepth);
      m[level] += node->val;
      solve(node->left, level + 1);
      solve(node->right, level + 1);
   }
   int deepestLeavesSum(TreeNode* root) {
      maxDepth = 0;
      m.clear();
      solve(root);
      return m[maxDepth];
   }
};
main(){
   TreeNode *root = new TreeNode(1);
   root−>left = new TreeNode(2);
   root−>right = new TreeNode(3);
   root−>left−>left = new TreeNode(4);
   root−>left−>right = new TreeNode(5);
   root−>right−>right = new TreeNode(6);
   root−>right−>right−>right = new TreeNode(4);
   root−>left−>left−>left = new TreeNode(7);
   Solution ob;
   cout << (ob.deepestLeavesSum(root));
}

Input

TreeNode *root = new TreeNode(1);
root−>left = new TreeNode(2);
root−>right = new TreeNode(3);
root−>left−>left = new TreeNode(4);
root−>left−>right = new TreeNode(5);
root−>right−>right = new TreeNode(6);
root−>right−>right−>right = new TreeNode(4);
root−>left−>left−>left = new TreeNode(7);

Output

11