Sum Of Left Leaves Problem

Description

LeetCode Problem 404.

Given the root of a binary tree, return the sum of all left leaves.

Example 1:

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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:

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Input: root = [1]
Output: 0
``````

Constraints:

• The number of nodes in the tree is in the range [1, 1000].
• -1000 <= Node.val <= 1000

Sample C++ Code

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/**
* 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 sumOfLeftLeaves(TreeNode* root) {
if (root == NULL)
return 0;
if (root->left == NULL)
return sumOfLeftLeaves(root->right);
if (root->left->left == NULL && root->left->right == NULL)
return root->left->val + sumOfLeftLeaves(root->right);
return sumOfLeftLeaves(root->left) + sumOfLeftLeaves(root->right);
}
};
``````