Largest subtree sum in a tree

class Solution {

  public:

    long long int ans = INT_MIN;

    long long  solve(Node* root){

        if(!root) return 0;

        long long left = solve(root->left);

        long long right = solve(root->right);

        ans= max(ans,left+right+root->data);

           return left+right+root->data;

    }

    int findLargestSubtreeSum(Node* root){

        solve(root);

        return ans;

        

    }

};