Sum of Left Leaves

Sum of Left Leaves

Find the sum of all left leaves in a given binary tree.

Example:

    3
   / \
  9  20
    /  \
   15   7

There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.

Solutions

🧠 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
{ 
    enum Leaf{R, L};
public:
    int sumOfLeftLeaves(TreeNode* node, Leaf pos = R)
    {
        if(!node)
            return 0;

        if(pos == L && !node->right && !node->left)
            return node->val;

        return sumOfLeftLeaves(node->right, R) + sumOfLeftLeaves(node->left, L);
    }
};