Submission #950501

#	Time	Username	Problem	Language	Result	Execution time	Memory
950501		andrei_boaca	Chorus (JOI23_chorus)	C++17	61 / 100	7044 ms	6748 KiB

chorus

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
const ll INF=1e17;
ll n,k,lga,lgb,makegood;
ll A[1000005],B[1000005];
struct date
{
    ll val,l,r;
} dp[1000005];
string str;
date combine(date a, date b)
{
    if(a.val<b.val)
        return a;
    if(a.val>b.val)
        return b;
    a.l=min(a.l,b.l);
    a.r=max(a.r,b.r);
    return a;
}
void solve(ll cost)
{
    for(int i=n;i>=1;i--)
    {
        dp[i]={INF,0,0};
        ll suma=0;
        ll C=0;
        int ind=i;
        for(int j=i;j<=n;j++)
        {
            while(ind<=n&&B[ind]<A[j])
            {
                suma++;
                ind++;
            }
            C+=suma;
            date a=dp[j+1];
            a.val+=C+cost;
            a.l++;
            a.r++;
            dp[i]=combine(dp[i],a);
        }
    }
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin>>n>>k;
    cin>>str;
    for(int i=0;i<str.size();i++)
    {
        if(str[i]=='A')
            A[++lga]=i+1;
        else
            B[++lgb]=i+1;
    }
    for(int i=1;i<=n;i++)
        if(A[i]>B[i])
        {
            ll x=A[i];
            A[i]=B[i];
            for(int j=i;j<=n;j++)
            {
                if(B[j]<x)
                {
                    B[j]++;
                    makegood++;
                }
                else
                    break;
            }
        }
    /*for(int i=n;i>=1;i--)
    {
        dp[i][0]=INF;
        for(int cnt=1;cnt<=k;cnt++)
        {
            ll suma=0;
            ll cost=0;
            int ind=i;
            dp[i][cnt]=INF;
            for(int j=i;j<=n;j++)
            {
                while(ind<=n&&B[ind]<A[j])
                {
                    suma++;
                    ind++;
                }
                cost+=suma;
                dp[i][cnt]=min(dp[i][cnt],cost+dp[j+1][cnt-1]);
            }
        }
    }*/
    ll st=-2e12;
    ll dr=2e12;
    while(st<=dr)
    {
        ll mij=(st+dr)/2;
        solve(mij);
        if(dp[1].l<=k&&dp[1].r>=k)
        {
            ll rez=dp[1].val-mij*k;
            cout<<rez+makegood;
            return 0;
        }
        if(dp[1].l>k)
            st=mij+1;
        else
            dr=mij-1;
    }
    return 0;
}

Compilation message (stderr)

chorus.cpp: In function 'int main()':
chorus.cpp:53:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |     for(int i=0;i<str.size();i++)
      |                 ~^~~~~~~~~~~

• Subtask 1: 16 / 16
• Subtask 2: 24 / 24
• Subtask 3: 21 / 21
• Subtask 4: 0 / 26
• Subtask 5: 0 / 13