leetcode-797-All-Paths-From-Source-to-Target

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描述

Given a directed, acyclic graph of N nodes. Find all possible paths from node 0 to node N-1, and return them in any order.

The graph is given as follows: the nodes are 0, 1, …, graph.length - 1. graph[i] is a list of all nodes j for which the edge (i, j) exists.

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Example:
Input: [[1,2], [3], [3], []] 
Output: [[0,1,3],[0,2,3]] 
Explanation: The graph looks like this:
0--->1
|    |
v    v
2--->3
There are two paths: 0 -> 1 -> 3 and 0 -> 2 -> 3.

Note:

  • The number of nodes in the graph will be in the range [2, 15].
  • You can print different paths in any order, but you should keep the order of nodes inside one path.

分析

解决方案1(Java)

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class Solution {
    public List<List<Integer>> allPathsSourceTarget(int[][] graph) {
        List<List<Integer>> result = new ArrayList();
        dfs(graph, result, 0, new ArrayList());
        return result;
    }
    
    private void dfs(int [][] graph, List<List<Integer>> result, int pos, List<Integer> path) {
        path.add(pos);
        
        if (graph[pos].length == 0) {
            result.add(new ArrayList(path));
        } else {
            for (int child: graph[pos]) {
                dfs(graph, result, child, path);
            }
        }
        path.remove(path.size()-1);
    }
}

题目来源