Submission #667625

#	Time	Username	Problem	Language	Result	Execution time	Memory
667625		berr	Star Trek (CEOI20_startrek)	C++17	0 / 100	3 ms	5076 KiB

startrek

#include <bits/stdc++.h>
using namespace std;
const int N=1e5+37;
vector<int> adj[N], adj2[N];
int huh, huuh, mod=1e9+7;

int mul(int x, int y){
    return (x*y)%mod;
}

int poww(int x, int y)
{
    if(y==0) return 1;
    int tmp=poww(x, y/2);

    if(y%2) return mul(tmp, mul(tmp, x));
    return mul(tmp, tmp); 
}
int dfs2(int v, int p, int d)
{
    int f=1;

    if(d%2==0) f=0;

    int count=0, val=0;

    for(auto i: adj2[v])
    {
        if(i==p) continue;

        if(dfs2(i, v, d+1))
        {
         
            if(d%2==0){
                f=1;
            }
        }
        else
        {
            if(d%2) f=0;
        }
    }




    return f;
}


int dfs(int v, int p, int d)
{
    int f=1;

    if(d%2==0) f=0;

    int count=0, val=0;

    for(auto i: adj[v])
    {
        if(i==p) continue;

        if(dfs(i, v, d+1))
        {
         
            if(d%2==0){
                f=1;
            }
        }
        else
        {
            if(d%2) f=0;
        }
    }

    if(huh==v)
    {   
        if(dfs2(huuh, 0, d+1)) 
        {
            if(d%2==0) f=1;
        }
        else
        {
            if(d%2) f=0;
        }
    }

    return f;
}


signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int n, d; cin>>n>>d;


    for(int i=0; i<n-1; i++){
        int x, y; cin>>x>>y;

        adj[x].push_back(y);
        adj[y].push_back(x);

        adj2[x].push_back(y);
        adj2[y].push_back(x);
    }

    int ans=0;

    {
        cout<<poww(2, d+1);
    }

}

Compilation message (stderr)

startrek.cpp: In function 'int dfs2(int, int, int)':
startrek.cpp:25:9: warning: unused variable 'count' [-Wunused-variable]
   25 |     int count=0, val=0;
      |         ^~~~~
startrek.cpp:25:18: warning: unused variable 'val' [-Wunused-variable]
   25 |     int count=0, val=0;
      |                  ^~~
startrek.cpp: In function 'int dfs(int, int, int)':
startrek.cpp:57:9: warning: unused variable 'count' [-Wunused-variable]
   57 |     int count=0, val=0;
      |         ^~~~~
startrek.cpp:57:18: warning: unused variable 'val' [-Wunused-variable]
   57 |     int count=0, val=0;
      |                  ^~~
startrek.cpp: In function 'int main()':
startrek.cpp:110:9: warning: unused variable 'ans' [-Wunused-variable]
  110 |     int ans=0;
      |         ^~~

• Subtask 1: 0 / 0
• Subtask 2: 0 / 7
• Subtask 3: 0 / 8
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 20
• Subtask 7: 0 / 20
• Subtask 8: 0 / 15