797. All Paths From Source to Target

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:

797. All Paths From Source to Target

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.

Constraints:

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

//from huahua

 

  • class Solution {
    public:
        vector<vector<int>> allPathsSourceTarget(vector<vector<int>>& graph) {
            vector<vector<int>> ans;
            vector<int> path(1,0); //定义长度为1,初始值为0的数组path
            dfs(graph,0,graph.size()-1,path,ans);
            return ans;
        }
    private:
        void dfs( vector<vector<int>>& graph,int cur,int dest,vector<int> &path,vector<vector<int>>& ans){
            if(cur==dest){
                ans.push_back(path);
                return;
            }
            for(int next:graph[cur]){
                path.push_back(next);
                dfs(graph,next,dest,path,ans);
                path.pop_back(); //删除path数组中最后一个元素
            }
        }
        
    };

     

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