Submission #580195

#	Time	Username	Problem	Language	Result	Execution time	Memory
580195		wdjpng	Boarding Passes (BOI22_passes)	C++17	5 / 100	42 ms	1612 KiB

passes

#include <bits/stdc++.h>

#define int long long
#define double long double
#define rep(i,n) for(int i =0; i<n; i++)
#define all(a) a.begin(),a.end()

using namespace std;


string s;
int n;
double f(int n)
{
    return ((double) n)*((double) (n-1))/4.0;
}

string ord;
vector<double>mem;
vector<vector<int>>pos;
int g;
// cost to add the group gr with all members of that group with and index <= to maxi boarding on the left
double cost(int bor, int gr, int maxi)
{
    double sum = 0;
    int firstr = maxi+1;

    sum+=f(pos[gr].size()-firstr) + f(firstr);


    vector<int>otherpos;
    rep(i,n) if(((1<<(s[i]-'A'))&bor)==0) otherpos.push_back(i);

    rep(i,firstr)
    {
        sum+=upper_bound(all(otherpos),pos[gr][i])-otherpos.begin();
    }

    for(int i = firstr; i < pos[gr].size(); i++) sum+=otherpos.end()-upper_bound(all(otherpos),pos[gr][i]);

    return sum;
}

vector<int>lookup;
double dfs(int bor)
{
    if(mem[bor]>-0.9) return mem[bor];


    double sol = 1e18;
    rep(ck,g)
    {
        int i=lookup[ck];
        if(!((1<<i)&bor)) continue;
        int nbor = bor^(1<<i);
        int start = -1, end = pos[i].size()-1;
        while(end-start>1)
        {
            int c = (start+end)/2;
            double l =cost(bor,i,c), r=cost(bor,i,c+1);
    
            if(r>=l) end=c;
            else start=c;
        };
        // double minn = 1e18;
        // rep(j,pos[i].size()) if(cost(bor,i,j)<minn) {minn=cost(bor,i,j); end=j;}


        sol=min(sol, cost(bor,i,end)+dfs(nbor));
    }
    return mem[bor] = sol;
}
signed main()
{
    cin>>s;
    s.size();
    n=s.size();

    double sum = f(n/2) + f((n+1)/2);
    cout.precision(300);
    
    char maxx=0;
    rep(i,n) maxx=max(maxx, s[i]);
    g=maxx-'A'+1;

    pos.resize(g);
   

    rep(i,n) pos[(s[i]-'A')].push_back(i);
    lookup.assign(g,0);
    rep(i,g) lookup[i]=i;
     mem.assign(1<<g,-1.0);
        mem[0]=0;
        cout<<dfs((1<<g)-1)<<'\n';
      
    
}

Compilation message (stderr)

passes.cpp: In function 'long double cost(long long int, long long int, long long int)':
passes.cpp:39:27: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |     for(int i = firstr; i < pos[gr].size(); i++) sum+=otherpos.end()-upper_bound(all(otherpos),pos[gr][i]);
      |                         ~~^~~~~~~~~~~~~~~~
passes.cpp: In function 'int main()':
passes.cpp:79:12: warning: unused variable 'sum' [-Wunused-variable]
   79 |     double sum = f(n/2) + f((n+1)/2);
      |            ^~~

• Subtask 1: 5 / 5
• Subtask 2: 0 / 25
• Subtask 3: 0 / 30
• Subtask 4: 0 / 40