797. All Paths From Source to Target

Link: https://leetcode.com/problems/all-paths-from-source-to-target/

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.

---

題目翻譯:

給定 N 個節點的有向非循環圖。查找從節點 0 到節點 N-1 的所有可能路徑，並以任何順序返回它們。

圖形給出如下：節點是 0,1，…，graph.length - 1. graph [i]是邊緣（i，j）存在的所有節點 j 的列表。

程式思路:

用 dfs 來實作此題目。

class Solution {
public:
    void dfs(int cur,vector<int> &path,vector<vector<int>> &paths,vector<vector<int>>& graph)
    {
        path.emplace_back(cur);
        if (cur == graph.size()-1)
        {
            paths.emplace_back(path);
        }else
            for(auto next : graph[cur])
            {
                dfs(next,path,paths,graph);
            }
        path.pop_back();
    }
    vector<vector<int>> allPathsSourceTarget(vector<vector<int>>& graph) {
        vector<vector<int>> paths;
        vector<int> path;
        dfs(0,path,paths,graph);
        return paths;
    }
};