sumofleftleaves.cpp

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int s=0;
	int sumOfLeftLeaves(TreeNode* root) {
		if(!root) return NULL;
		if(root->left && !root->left->left && !root->left->right){
			s+=root->left->val;
		}
		
		sumOfLeftLeaves(root->right);  
        sumOfLeftLeaves(root->left);     
		return s;
    }
};