75th LeetCode Weekly Contest 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.

问0->n-1有几条路径

其实没什么，就是看输入有点不懂怎么建图，把图建立好，我们dfs就好了

class Solution {
public:
    int Mp[30][30];
    vector<vector<int>>ans;
    vector<int>tmp;
    void dfs(int n,int len){
        if(len-1==n){
            ans.push_back(tmp);
            return;
        }
        for(int i=0;i<len;i++){
            if(Mp[n][i]){
                tmp.push_back(i);
                dfs(i,len);
                tmp.pop_back();
            }
        }
    }
    vector<vector<int>> allPathsSourceTarget(vector<vector<int>>& graph) {
        int len=graph.size();
        for(int i=0;i<len;i++){
            for(int j=0;j<graph[i].size();j++){
                Mp[i][graph[i][j]]=1;
            }
        }
        tmp.clear();
        ans.clear();
        tmp.push_back(0);
        dfs(0,len);
        return ans;
        
    }
};