LeetCode797. All Paths From Source to Target

一、题目

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]]

Constraints:

n == graph.length
2 <= n <= 15
0 <= graph[i][j] < n
graph[i][j] != i (i.e., there will be no self-loops).
All the elements of graph[i] are unique.
The input graph is guaranteed to be a DAG.

二、题解

class Solution {
public:
    vector<vector<int>> res;
    vector<int> path;
    void dfs(vector<vector<int>>& graph,int x){
        if(x == graph.size() - 1){
            res.push_back(path);
            return;
        }
        for(int i = 0;i < graph[x].size();i++){
            path.push_back(graph[x][i]);
            dfs(graph,graph[x][i]);
            path.pop_back();
        }
    }
    vector<vector<int>> allPathsSourceTarget(vector<vector<int>>& graph) {
        path.push_back(0);
        dfs(graph,0);
        return res;
    }
};