代码随想录Day64

98.所有可达路径

题目：98. 所有可达路径 (kamacoder.com)

思路：果断放弃

答案

import java.util.*;public class Main {private static List<List<Integer>> adjList;private static List<List<Integer>> allPaths;private static int target;public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int n = scanner.nextInt();int m = scanner.nextInt();adjList = new ArrayList<>();for (int i = 0; i < n + 1; i++) {adjList.add(new ArrayList<>());}for (int i = 0; i < m; i++) {int s = scanner.nextInt();int t = scanner.nextInt();adjList.get(s).add(t);}target = n;allPaths = new ArrayList<>();List<Integer> currentPath = new ArrayList<>();currentPath.add(1);findAllPaths(1, currentPath);if (allPaths.isEmpty()) {System.out.println("-1");} else {for (List<Integer> path : allPaths) {System.out.println(formatPath(path));}}scanner.close();}private static void findAllPaths(int currentNode, List<Integer> currentPath) {if (currentNode == target) {allPaths.add(new ArrayList<>(currentPath));return;}for (int nextNode : adjList.get(currentNode)) {currentPath.add(nextNode);findAllPaths(nextNode, currentPath);currentPath.remove(currentPath.size() - 1);}}private static String formatPath(List<Integer> path) {StringBuilder sb = new StringBuilder();for (int i = 0; i < path.size(); i++) {sb.append(path.get(i));if (i < path.size() - 1) {sb.append(" ");}}return sb.toString();}
}

小结

• 注意，要按照题目格式输出
• 使用回溯算法
  • 确认递归函数，参数
  • 确定终止条件
  • 处理目前搜索节点出发的路径