二叉树中和为某一值的路径
题目:输入一颗二叉树和一个整数,打印出二叉树中结点值的和为输入整数的所有路径。路径定义为从树的根结点开始往下一直到叶结点所经过的结点形成一条路径。
思路:递归回溯。先从先序遍历递归到叶子节点然后回溯所有的解。满足就加入结果集合。
实现代码:
import java.util.ArrayList; /** public class TreeNode { int val = 0; TreeNode left = null; TreeNode right = null; public TreeNode(int val) { this.val = val; } } */ public class Solution { private ArrayList<ArrayList<Integer>> retList; private ArrayList<Integer> oneList; public Solution() { retList = new ArrayList<ArrayList<Integer>>(); oneList = new ArrayList<Integer>(); } public ArrayList<ArrayList<Integer>> FindPath(TreeNode root,int target) { if(root == null) return retList; oneList.add(root.val); target -= root.val; if(target == 0 && root.left == null && root.right == null) { retList.add(new ArrayList<Integer>(oneList)); } FindPath(root.left, target); FindPath(root.right, target); oneList.remove(oneList.size()-1); return retList; } }
作者:Pickle
声明:对于转载分享我是没有意见的,出于对博客园社区和作者的尊重一定要保留原文地址哈。
致读者:坚持写博客不容易,写高质量博客更难,我也在不断的学习和进步,希望和所有同路人一道用技术来改变生活。觉得有点用就点个赞哈。
![](https://images2015.cnblogs.com/blog/735119/201701/735119-20170111112835275-168981902.gif)
![](https://images2015.cnblogs.com/blog/735119/201701/735119-20170111112841431-2047172832.jpg)
![](https://images2015.cnblogs.com/blog/735119/201701/735119-20170111112847494-1544911856.jpg)
![](https://images2015.cnblogs.com/blog/735119/201701/735119-20170111112904385-918783221.jpg)
![](https://images2015.cnblogs.com/blog/735119/201701/735119-20170111120143119-1302805212.jpg)
![](https://images2015.cnblogs.com/blog/735119/201701/735119-20170111112856369-1466718103.jpg)
![](https://images2015.cnblogs.com/blog/735119/201701/735119-20170111112830416-794416355.jpg)
![](https://images2015.cnblogs.com/blog/735119/201701/735119-20170111113919510-1155220901.gif)