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+1];
bool vis[MAXN+1];

void init(){
    for (int i = 1; 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==0) return true;
    //当要求的K大于 i 到 j 的长度，当 I ==J 时，k<0
    if(k>0){
        vis[begin] = true;
        for(int i=0;i<G[begin].size();i++){
            if(!vis[edges[G[begin][i]].t]) 
                return search_k_path(edges[G[begin][i]].t,end,k-1);
        }
        vis[begin] = false;
    }
    return false;
}



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

    int s,e;
    for(int i= 0 ;i<7;i++){
        cin>>s>>e;
        edges.push_back(edge(s,e));
        G[s].push_back(edges.size()-1);
        edges.push_back(edge(e,s));
        G[e].push_back(edges.size()-1);
    }    
    init();
    cout <<search_k_path(1,5,2)<<endl;

    return 0;
}