Submission #850423

#	Time	Username	Problem	Language	Result	Execution time	Memory
850423		Ahmed57	Boarding Passes (BOI22_passes)	C++17	60 / 100	599 ms	40624 KiB

passes

#include <bits/stdc++.h>
using namespace std;
int c = 0;
vector<int> arr[15];
short pref[10001][1024],suf[10001][1024];
long double dp[1024];
int sz;
long double ge(long double x){
    if(x<=1)return 0;
    return (x*(x-1))/4.0;
}
int main(){
    string s;cin>>s;
    map<char,int> x;
    int ind = -1;
    sz = s.size();
    for(auto i:s){
        ind++;
        if(x[i]==0){
            x[i] = ++c;
            arr[c-1].push_back(ind);
        }else{
            arr[x[i]-1].push_back(ind);
        }
    }
    if(c==1){
        long long x = s.size();
    if(x<=2){
        cout<<0.0<<endl;return 0;
    }
    else if(x==3){
        cout<<0.5<<endl;
        return 0;
    }
    long double v1 = x/2 , v2 = x-v1;
    long double ans = ((v1*(v1-1)/2)*(v1*(v1-1)/2))/(v1*(v1-1));
    swap(v1,v2);
    ans+= ((v1*(v1-1)/2)*(v1*(v1-1)/2))/(v1*(v1-1));
    cout<<setprecision(3)<<fixed<<ans<<endl;
        return 0;
    }
    for(int mask = 0;mask<(1<<c);mask++){
        for(int i = 0;i<sz;i++){
            pref[i][mask] = (mask&(1<<(x[s[i]]-1))?1:0);
            if(i)pref[i][mask]+=pref[i-1][mask];
        }
        for(int i = sz-1;i>=0;i--){
            suf[i][mask] =(mask&(1<<(x[s[i]]-1))?1:0);
            if(i<sz-1)suf[i][mask]+=suf[i+1][mask];
        }
    }
    for(int mask = (1<<c)-1;mask>=0;mask--){
    if(mask==(1<<c)-1){
        dp[mask] = 0;
        continue;
    }
    dp[mask] = 1000000000.0;
    for(int j = 0;j<c;j++){
        if(!(mask&(1<<j))){
            long long all = 0 , xd = 0;
            for(int e = 0;e<arr[j].size();e++){
                all+=suf[arr[j][e]][mask];
            }
            dp[mask] = min(dp[mask],dp[mask^(1<<j)]+all+xd+ge(arr[j].size()));
            for(int e = 0;e<arr[j].size();e++){
                all-=suf[arr[j][e]][mask];
                xd+=pref[arr[j][e]][mask];
                dp[mask] = min(dp[mask],dp[mask^(1<<j)]+all+xd+ge(e+1)+ge(arr[j].size()-e-1));
            }
        }
    }
    }
    cout<<setprecision(4)<<fixed<<dp[0]<<endl;
    return 0;
}

Compilation message (stderr)

passes.cpp: In function 'int main()':
passes.cpp:61:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |             for(int e = 0;e<arr[j].size();e++){
      |                           ~^~~~~~~~~~~~~~
passes.cpp:65:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |             for(int e = 0;e<arr[j].size();e++){
      |                           ~^~~~~~~~~~~~~~

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