package io.github.dunwu.algorithm.tree.btree;
import io.github.dunwu.algorithm.tree.TreeUtils;
import org.junit.jupiter.api.Assertions;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
/**
* <code>二叉树的所有路径</code> 算法实现
*
* <pre>
* 给定一个二叉树，返回所有从根节点到叶子节点的路径。
*
* 说明: 叶子节点是指没有子节点的节点。
*
* 示例:
*
* 输入:
*
* 1
* / \
* 2 3
* \
* 5
*
* 输出: ["1->2->5", "1->3"]
*
* 解释: 所有根节点到叶子节点的路径为: 1->2->5, 1->3
* </pre>
*
* @see <a href="https://leetcode-cn.com/problems/binary-tree-paths/">二叉树的所有路径</a>
*/
public class 二叉树的所有路径 {
public static void main(String[] args) {
TreeNode tree = TreeUtils.buildTree(1, 2, 3, 5);
System.out.println("result = " + binaryTreePaths(tree));
Assertions.assertArrayEquals(Arrays.asList("1->2->5", "1->3").toArray(),
binaryTreePaths(tree).toArray(new String[0]));
}
public static List<String> binaryTreePaths(TreeNode root) {
List<String> paths = new LinkedList<>();
recordPath(root, "", paths);
return paths;
}
private static void recordPath(TreeNode node, String path, List<String> paths) {
if (node == null) return;
path += node.val;
if (node.left == null && node.right == null) {
paths.add(path);
} else {
path += "->";
recordPath(node.left, path, paths);
recordPath(node.right, path, paths);
}
}
}
