题目不难，很快ac,纯粹靠手感。https://oj.leetcode.com/problems/sum-root-to-leaf-numbers/
1 /** 2 * Definition for binary tree 3 * public class TreeNode { 4 * int val; 5 * TreeNode left; 6 * TreeNode right; 7 * TreeNode(int x) { val = x; } 8 * } 9 */ 10 public class Solution { 11 private int sum=0; 12 public int sumNumbers(TreeNode root) { 13 if(root==null) return 0; 14 15 16 17 sum(root,""+root.val); 18 return sum; 19 20 } 21 public void sum(TreeNode root,String s) 22 { 23 24 if(root.left==null&&root.right==null) 25 { 26 sum+=Integer.parseInt(s); 27 } 28 else 29 { 30 if(root.left!=null) sum(root.left,s+root.left.val); 31 if(root.right!=null) sum(root.right,s+root.right.val); 32 33 34 35 } 36 37 38 39 } 40 41 }