g0101_0200.s0113_path_sum_ii.Solution Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java21 Show documentation
Show all versions of leetcode-in-java21 Show documentation
Java-based LeetCode algorithm problem solutions, regularly updated
package g0101_0200.s0113_path_sum_ii;
// #Medium #Depth_First_Search #Tree #Binary_Tree #Backtracking #Data_Structure_II_Day_16_Tree
// #2022_06_23_Time_1_ms_(100.00%)_Space_44.7_MB_(53.10%)
import com_github_leetcode.TreeNode;
import java.util.ArrayList;
import java.util.List;
/*
* Definition for a binary tree node.
* public 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;
* }
* }
*/
/**
* 113 - Path Sum II\.
*
* Medium
*
* Given the `root` of a binary tree and an integer `targetSum`, return _all **root-to-leaf** paths where the sum of the node values in the path equals_ `targetSum`_. Each path should be returned as a list of the node **values** , not node references_.
*
* A **root-to-leaf** path is a path starting from the root and ending at any leaf node. A **leaf** is a node with no children.
*
* **Example 1:**
*
* ![](https://assets.leetcode.com/uploads/2021/01/18/pathsumii1.jpg)
*
* **Input:** root = [5,4,8,11,null,13,4,7,2,null,null,5,1], targetSum = 22
*
* **Output:** [[5,4,11,2],[5,8,4,5]]
*
* **Explanation:** There are two paths whose sum equals targetSum: 5 + 4 + 11 + 2 = 22 5 + 8 + 4 + 5 = 22
*
* **Example 2:**
*
* ![](https://assets.leetcode.com/uploads/2021/01/18/pathsum2.jpg)
*
* **Input:** root = [1,2,3], targetSum = 5
*
* **Output:** []
*
* **Example 3:**
*
* **Input:** root = [1,2], targetSum = 0
*
* **Output:** []
*
* **Constraints:**
*
* * The number of nodes in the tree is in the range `[0, 5000]`.
* * `-1000 <= Node.val <= 1000`
* * `-1000 <= targetSum <= 1000`
**/
public class Solution {
public List> pathSum(TreeNode root, int targetSum) {
List> res = new ArrayList<>();
if (root == null) {
return res;
}
recur(res, new ArrayList<>(), 0, targetSum, root);
return res;
}
private void recur(
List> res, ArrayList al, int sum, int targetSum, TreeNode root) {
if (root == null) {
return;
}
al.add(root.val);
sum += root.val;
if (sum == targetSum && root.left == null && root.right == null) {
res.add(new ArrayList<>(al));
}
recur(res, al, sum, targetSum, root.left);
recur(res, al, sum, targetSum, root.right);
al.remove(al.size() - 1);
}
}