判断无向图两点间是否存在长度为K的路径

 #include <iostream>
 #include <vector>
 #define MAXN  5
 using namespace std;

 struct edge
 {
     int f,t;
     edge(int f, int t) :f(f), t(t) {}
 };

 vector<edge> edges;
 vector<int> G[MAXN+];
 bool vis[MAXN+];

 void init(){
     for (int i = ; i <= MAXN; i++)
         vis[i] = false;
 }

 //通过缩短路径方法求解
 bool search_k_path(int begin,int end,int k){
     if(begin==end && k==) return true;
     //当要求的K大于 i 到 j 的长度，当 I ==J 时，k<0
     if(k>){
         vis[begin] = true;
         for(int i=;i<G[begin].size();i++){
             if(!vis[edges[G[begin][i]].t])
                 return search_k_path(edges[G[begin][i]].t,end,k-);
         }
         vis[begin] = false;
     }
     return false;
 }

 int main(int argc, char const *argv[])
 {
     //input data

     int s,e;
     for(int i=  ;i<;i++){
         cin>>s>>e;
         edges.push_back(edge(s,e));
         G[s].push_back(edges.size()-);
         edges.push_back(edge(e,s));
         G[e].push_back(edges.size()-);
     }
     init();
     cout <<search_k_path(,,)<<endl;

     return ;
 }