二叉树叶子节点之和

计算二叉树的叶子节点之和

样例

样例 1:

输入：{1,2,3,4}
输出：7
解释：
    1
   / \
  2   3
 /
4
3+4=7

样例 2:

输入：{1,#,3}
输出：3
解释：
    1
      \
       3

输入测试数据 (每行一个参数)如何理解测试数据？

 

/**
 * Definition of TreeNode:
 * class TreeNode {
 * public:
 *     int val;
 *     TreeNode *left, *right;
 *     TreeNode(int val) {
 *         this->val = val;
 *         this->left = this->right = NULL;
 *     }
 * }
 */

class Solution {
public:
    /**
     * @param root: the root of the binary tree
     * @return: An integer
     */
     
    int  sum;
    int leafSum(TreeNode * root)
    {
        // write your code here
        if(root == NULL)
            return 0;
        sum = 0;
        return mysum(root);
    }
    
    int mysum(TreeNode * root)
    {
        if(root != NULL)
        {
            mysum(root->left);
            if(root->left == NULL  && root->right == NULL)
                sum += root->val;
            mysum(root->right);
            return sum;
        }
    }
};