IsBinarySumTree.cpp

// { Driver Code Starts
#include <bits/stdc++.h>
using namespace std;

struct Node
{
    int data;
    struct Node *left;
    struct Node *right;
};
// Utility function to create a new Tree Node
Node* newNode(int val)
{
    Node* temp = new Node;
    temp->data = val;
    temp->left = NULL;
    temp->right = NULL;

    return temp;
}
// Function to Build Tree
Node* buildTree(string str)
{
    // Corner Case
    if(str.length() == 0 || str[0] == 'N')
            return NULL;

    // Creating vector of strings from input
    // string after spliting by space
    vector<string> ip;

    istringstream iss(str);
    for(string str; iss >> str; )
        ip.push_back(str);

    // Create the root of the tree
    Node* root = newNode(stoi(ip[0]));

    // Push the root to the queue
    queue<Node*> queue;
    queue.push(root);

    // Starting from the second element
    int i = 1;
    while(!queue.empty() && i < ip.size()) {

        // Get and remove the front of the queue
        Node* currNode = queue.front();
        queue.pop();

        // Get the current node's value from the string
        string currVal = ip[i];

        // If the left child is not null
        if(currVal != "N") {

            // Create the left child for the current node
            currNode->left = newNode(stoi(currVal));

            // Push it to the queue
            queue.push(currNode->left);
        }

        // For the right child
        i++;
        if(i >= ip.size())
            break;
        currVal = ip[i];

        // If the right child is not null
        if(currVal != "N") {

            // Create the right child for the current node
            currNode->right = newNode(stoi(currVal));

            // Push it to the queue
            queue.push(currNode->right);
        }
        i++;
    }

    return root;
}

// Should return true if tree is Sum Tree, else false
class Solution {
    public:
    int sumTree(Node* root, bool& flag) {
        if (!root) return 0;

        int oldValue = root->data;
        int height = sumTree(root->left, flag) + sumTree(root->right, flag);
        if((root->left || root->right) && height != root->data) {
            flag = false;
            return height + oldValue;
        }

        return height + oldValue;
    }

    bool isSumTree(Node* root) {
        bool flag = true;
        if (!root) return flag;
        sumTree(root, flag);
        return flag;
    }
};

int main()
{

    int t;
	scanf("%d ",&t);
    while(t--)
    {
        string s;
		getline(cin,s);
        Node* root = buildTree(s);
        Solution ob;
        cout <<ob.isSumTree(root) << endl;
    }
    return 1;
}