Submission #863717

#	Time	Username	Problem	Language	Result	Execution time	Memory
863717		alittlemiddle	Paths (BOI18_paths)	C++14	100 / 100	312 ms	486500 KiB

paths

#include <bits/stdc++.h>
#define task
using namespace std;
const int maxn=3e5+4;
const int maxk=6;
const int BASE=33;
int n,m,k,u,v;
vector <int> mask[maxk][maxk];
vector <int> adj[maxn];
long long dp[maxn][maxk][BASE];
long long ans=0;
int col[maxn];
void input()
{
    cin>>n>>m>>k;
    for (int i=1;i<=n;i++)
    {
        cin>>col[i];
    }
    for (int i=1;i<=m;i++)
    {
        cin>>u>>v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for (int i=0;i<(1<<k);i++)
    {
        int x=0,y=i;
        while (y>0) {x+=y%2; y/=2;}
        for (int j=1;j<=k;j++)
        if (i&(1<<(j-1))) mask[x][j].push_back(i);
    }
}
void solve()
{
    for (int i=1;i<=n;i++)
    {
        dp[i][1][1<<(col[i]-1)]=1;
    }
    for (int i=2;i<=k;i++)
    {
        for (int j=1;j<=n;j++)
        {

            for (int x:mask[i][col[j]])
            {
                for (int y:adj[j])
                dp[j][i][x]+=dp[y][i-1][x^(1<<(col[j]-1))];
                ans+=dp[j][i][x];
                //cout<<j<<" "<<i<<" "<<x<<" "<<dp[j][i][x]<<"\n";
            }
        }
    }
    cout<<ans;

}
signed main()
{
    if (fopen(task".INP","r"))
    {
        freopen(task".INP", "r", stdin);
        freopen(task".OUT", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    input();
    solve();


}

Compilation message (stderr)

paths.cpp: In function 'int main()':
paths.cpp:61:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   61 |         freopen(task".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
paths.cpp:62:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |         freopen(task".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 23 / 23
• Subtask 2: 20 / 20
• Subtask 3: 27 / 27
• Subtask 4: 30 / 30