Sum of Left Leaves
Problem Statement - link #
Given the root of a binary tree, return the sum of all left leaves.
Examples #
Example 1:
Input: root = [3,9,20,null,null,15,7]
Output: 24
Explanation: There are two left leaves in the binary tree, with values 9 and 15 respectively.
Example 2:
Input: root = [1]
Output: 0
Constraints #
- The number of nodes in the tree is in the range
[1, 1000]. -1000 <= Node.val <= 1000
Solutions #
/**
* 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 res = 0;
void rc(TreeNode* root){
if(!root or (!root->left and !root->right)) return;
if(root->left and !root->left->left and !root->left->right) res+= root->left->val;
rc(root->left);
rc(root->right);
}
int sumOfLeftLeaves(TreeNode* root) {
rc(root);
return res;
}
};