sicily 1155. Can I Post the lette

#include<iostream>#include <vector>#include <queue>#include <cstring>using namespace std;int N,M,a,b;const int num=201;bool visited[num];vector<int>vec[num];int main(){    while (cin>>N&&N!=0)    {        memset(visited,false,sizeof(visited));//      vec.clear();  //error cause we define a array of vec,it has "num" numbers of individual vector.        fill(vec,vec+N,vector<int>());  //from vec to vec+N set all values to  instrutor:vector<int>()        queue<int>que;        cin>>M;        while (M--)        {            cin>>a>>b;            vec[a].push_back(b);        }        visited[0]=true;        que.push(0);        //BFS        while (!que.empty()){            int temp=que.front();            que.pop();            for(int i=0;i<vec[temp].size();i++){                int a=vec[temp][i];                if (!visited[a]){                    que.push(a);                    visited[a]=true;                }            }        }        //output        if (visited[N-1]==true)            cout<<"I can post the letter"<<endl;        else            cout<<"I can't post the letter"<<endl;    }    return 0;}