题目:
计算给定二叉树的所有左叶子之和。
示例:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int sumOfLeftLeaves(TreeNode* root) {
int res=0;
if(!root || (!root->left && !root->right)) return 0;
if(root->left && (!root->left->left && !root->left->right)) res+=root->left->val;
res+=sumOfLeftLeaves(root->left);
res+=sumOfLeftLeaves(root->right);
return res;
}
};