LeetCode: Sum Root to Leaf Numbers

少数次过

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    void dfs(TreeNode *root, int &ret, int tmp) {
        if (!root) return;
        if (!root->left && !root->right) ret += tmp*10+root->val;
        else {
            if (root->left) dfs(root->left, ret, tmp*10+root->val);
            if (root->right) dfs(root->right, ret, tmp*10+root->val);
        }
    }
    int sumNumbers(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (!root) return 0;
        int ret = 0;
        dfs(root, ret, 0);
        return ret;
    }
};

 C#

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int SumNumbers(TreeNode root) {
        if (root == null) return 0;
        int ans = 0;
        dfs(root, ref ans, 0);
        return ans;
    }
    public void dfs(TreeNode root, ref int ans, int tmp) {
        if (root == null) return;
        if (root.left == null && root.right == null) ans += tmp * 10 + root.val;
        else {
            if (root.left != null) dfs(root.left, ref ans, tmp * 10 + root.val);
            if (root.right != null) dfs(root.right, ref ans, tmp * 10 + root.val);
        }
    }
}