### Path Sum II

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] ]

``````import java.util.*;

/**
* Created by gzdaijie on 16/6/9
*/
public class Solution {
public List<List<Integer>> pathSum(TreeNode root, int sum) {
List<List<Integer>> result = new ArrayList<>();
ArrayList<Integer> tmp = new ArrayList<>();
if (root != null) helper(result, tmp, root, sum);
return result;
}

private void helper(List<List<Integer>> result, ArrayList<Integer> item, TreeNode root, int sum) {

if (root.left == null && root.right == null) {
if (sum == root.val) result.add((List<Integer>) item.clone());
return;
}

if (root.left != null) {
helper(result, item, root.left, sum - root.val);
item.remove(item.size() - 1);
}

if (root.right != null) {
helper(result, item, root.right, sum - root.val);
item.remove(item.size() - 1);
}
}
}
``````
updated 2016-06-09 15:52:39