Shared code

#include<iostream>
#include<vector>
#include<queue>
#include<algorithm>
using namespace std;
vector<bool>vis;
long long MOD=1e9+7;
int n;
int dfs(int p,vector<int>*graph,vector<long long>&wt){
  vis[p]=true;
  if(p==n)return wt[n]=1;
  if(wt[p]!=0)return wt[p];
  long long ans=0;
  for(int aa:graph[p]){
    if(vis[aa])ans=(ans+wt[aa])%MOD;
    else ans=(ans+dfs(aa,graph,wt))%MOD;
  }
  return wt[p]=ans%MOD;
}
int main(){
  int m,a,b,top;
  cin>>n>>m;
  vector<int>graph[n+1];
  vector<long long>ways(n+1,0);
  vis.resize(n+1,0);
  for(int i=0;i<m;i++){
    cin>>a>>b;
    graph[a].push_back(b);
  }
  cout<<dfs(1,graph,ways);
  return 0;
}