1. 题目
2. 思路
(1) DFS
- 利用深度优先搜索遍历二叉树，并利用栈记录根结点到当前结点的路径，若当前结点为叶子结点且当前路径之和为目标值，则将当前路径加入结果集。
3. 代码
import java.util.*;
public class Test {
public static void main(String[] args) {
}
}
class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode() {
}
TreeNode(int val) {
this.val = val;
}
TreeNode(int val, TreeNode left, TreeNode right) {
this.val = val;
this.left = left;
this.right = right;
}
}
class Solution {
private List<List<Integer>> res = new ArrayList<>();
private LinkedList<Integer> stack = new LinkedList<>();
public List<List<Integer>> pathSum(TreeNode root, int targetSum) {
dfs(root, targetSum);
return res;
}
private void dfs(TreeNode root, int targetSum) {
if (root == null) {
return;
}
stack.offerLast(root.val);
targetSum -= root.val;
if (root.left == null && root.right == null && targetSum == 0) {
res.add(new ArrayList<>(stack));
}
dfs(root.left, targetSum);
dfs(root.right, targetSum);
stack.pollLast();
}
}