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  • 0797. All Paths From Source to Target (M)

    All Paths From Source to Target (M)

    题目

    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.

    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.

    题意

    在一个有向无环图中找到所有从结点0到结点n-1的路径。

    思路

    回溯法。


    代码实现

    Java

    class Solution {
        public List<List<Integer>> allPathsSourceTarget(int[][] graph) {
            List<List<Integer>> ans = new ArrayList<>();
            dfs(graph, 0, graph.length - 1, new ArrayList<>(), ans);
            return ans;
        }
    
        private void dfs(int[][] graph, int u, int v, List<Integer> tmp, List<List<Integer>> ans) {
            tmp.add(u);
    
            if (u == v) {
                ans.add(new ArrayList<>(tmp));
            } else {
                for (int i = 0; i < graph[u].length; i++) {
                    dfs(graph, graph[u][i], v, tmp, ans);
                }
            }
    
            tmp.remove(tmp.size() - 1);
        }
    }
    
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  • 原文地址:https://www.cnblogs.com/mapoos/p/13375455.html
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