LeetCode 404. 左叶子之和

题目链接：https://leetcode-cn.com/problems/sum-of-left-leaves/

计算给定二叉树的所有左叶子之和。

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */

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