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] ]
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public List<List<Integer>> pathSum(TreeNode root, int sum) { List<List<Integer>> res = new ArrayList<List<Integer>>(); List<Integer> list = new ArrayList<Integer>(); solve(root, sum, res, list); return res; } private void solve(TreeNode root, int sum, List<List<Integer>> res, List<Integer> list) { if (root == null) { return; } list.add(root.val); sum -= root.val; if (root.left == null && root.right == null) { if (sum == 0) { res.add(new ArrayList<Integer>(list)); } } else { if (root.left != null) { solve(root.left, sum, res, list); } if (root.right != null) { solve(root.right, sum, res, list); } } list.remove(list.size()-1); } }