Binary Tree Path Sum
ID: 376; easy; 二叉树的路径和
Last updated
ID: 376; easy; 二叉树的路径和
Last updated
/**
* Definition of TreeNode:
* public class TreeNode {
* public int val;
* public TreeNode left, right;
* public TreeNode(int val) {
* this.val = val;
* this.left = this.right = null;
* }
* }
*/
public class Solution {
/*
* @param root: the root of binary tree
* @param target: An integer
* @return: all valid paths
*/
public List<List<Integer>> binaryTreePathSum(TreeNode root, int target) {
List<List<Integer>> result = new ArrayList<>();
if (root == null) return result;
List<Integer> path = new ArrayList<>();
path.add(root.val);
pathSumHelper(root, path, target, result);
return result;
}
private void pathSumHelper(TreeNode root, List<Integer> path, int target, List<List<Integer>> result) {
if (root.left == null && root.right == null) {
if (root.val == target) {
result.add(new ArrayList<Integer>(path));
}
return;
}
if (root.left != null) {
path.add(root.left.val);
pathSumHelper(root.left, path, target - root.val, result);
path.remove(path.size() - 1);
}
if (root.right != null) {
path.add(root.right.val);
pathSumHelper(root.right, path, target - root.val, result);
path.remove(path.size() - 1);
}
}
}