797. All Paths From Source to Target
作者：互联网
Given a directed acyclic graph (DAG) of n nodes labeled from 0 to n - 1, find all possible paths from node 0 to node n - 1, and return them in any order.
The graph is given as follows: graph[i] is a list of all nodes you can visit from node i (i.e., there is a directed edge from node i to node graph[i][j]).
Example 1:
Input: graph = [[1,2],[3],[3],[]] Output: [[0,1,3],[0,2,3]] Explanation: There are two paths: 0 -> 1 -> 3 and 0 -> 2 -> 3.
Example 2:
Input: graph = [[4,3,1],[3,2,4],[3],[4],[]] Output: [[0,4],[0,3,4],[0,1,3,4],[0,1,2,3,4],[0,1,4]]
Example 3:
Input: graph = [[1],[]] Output: [[0,1]]
Example 4:
Input: graph = [[1,2,3],[2],[3],[]] Output: [[0,1,2,3],[0,2,3],[0,3]]
Example 5:
Input: graph = [[1,3],[2],[3],[]] Output: [[0,1,2,3],[0,3]]
1 class Solution {
2 public List<List<Integer>> allPathsSourceTarget(int[][] graph) {
3 List<List<Integer>> allLists = new ArrayList<>();
4 helper(0, graph.length - 1, graph, new HashSet<>(), allLists, new ArrayList<>());
5 return allLists;
6 }
7
8 private void helper(int current, int target, int[][] graph, Set<Integer> visited, List<List<Integer>> allLists, List<Integer> singleList) {
9 singleList.add(current);
10 visited.add(current);
11 if (current == target) {
12 allLists.add(new ArrayList<>(singleList));
13 visited.remove(current);
14 singleList.remove(singleList.size() - 1);
15 return;
16 }
17
18 for (int neighbor : graph[current]) {
19 if (!visited.contains(neighbor)) {
20 helper(neighbor, target, graph, visited, allLists, singleList);
21 }
22 }
23 visited.remove(current);
24 singleList.remove(singleList.size() - 1);
25 }
26 }
or
1 class Solution {
2 public List<List<Integer>> allPathsSourceTarget(int[][] graph) {
3 List<List<Integer>> allLists = new ArrayList<>();
4 helper(0, graph.length - 1, graph, new HashSet<>(), allLists, new ArrayList<>());
5 return allLists;
6 }
7
8 private void helper(int current, int target, int[][] graph, Set<Integer> visited, List<List<Integer>> allLists, List<Integer> singleList) {
9 singleList.add(current);
10 visited.add(current);
11 if (current == target) {
12 allLists.add(new ArrayList<>(singleList));
13 }
14
15 for (int neighbor : graph[current]) {
16 if (!visited.contains(neighbor)) {
17 helper(neighbor, target, graph, visited, allLists, singleList);
18 }
19 }
20 visited.remove(current);
21 singleList.remove(singleList.size() - 1);
22 }
23 }
标签：797,Paths,Target,int,graph,current,allLists,singleList,visited 来源： https://www.cnblogs.com/beiyeqingteng/p/14195344.html