[LeetCode]113. Path Sum II

https://leetcode.com/problems/path-sum-ii/

找出所有根节点到叶子节点的路径

public class Solution {
public List<List<Integer>> pathSum(TreeNode root, int sum) {
List<List<Integer>> res = new LinkedList();
pathSum(root, sum, res, new LinkedList());
return res;
}
private void pathSum(TreeNode root, int sum, List<List<Integer>> res, List<Integer> list) {
if (root == null) {
return;
}
list.add(root.val);
if (root.left == null && root.right == null && root.val == sum) {
res.add(new LinkedList(list));
// 特殊情况也不要忘了删除！
list.remove(list.size() - 1);
return;
}
pathSum(root.left, sum - root.val, res, list);
pathSum(root.right, sum - root.val, res, list);
list.remove(list.size() - 1);
}
}