Path Sum II

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Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5             / \            4   8           /   / \          11  13  4         /  \    / \        7    2  5   1

return

[   [5,4,11,2],   [5,8,4,5]]

要写出路径和满足要求的所有路径 典型的回溯法递归求解 代码如下：

public class Solution {    public  List<List<Integer>> pathSum(TreeNode root, int sum) {List<List<Integer>> res=new ArrayList<List<Integer>>(0);List<Integer> tmp=new ArrayList<Integer>();pathsearch(res, tmp, sum, 0, root);return res;}public  void pathsearch(List<List<Integer>> res,List<Integer> tmp,int sum,int cur,TreeNode root){if(root==null)return;List<Integer> ntmp=new ArrayList<Integer>();ntmp.addAll(tmp);ntmp.add(root.val);if(root.left==null&&root.right==null){if(sum==cur+root.val){res.add(ntmp);}return;}if(root.left!=null){pathsearch(res, ntmp, sum, cur+root.val, root.left);}if(root.right!=null){pathsearch(res, ntmp, sum, cur+root.val, root.right);}}}

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