Submission #935165

#	Time	Username	Problem	Language	Result	Execution time	Memory
935165		kim	Chorus (JOI23_chorus)	C++17	40 / 100	7042 ms	12772 KiB

chorus

#include<bits/stdc++.h>
using namespace std;
using ll=long long;
using pii=pair<int,int>;
#define f first
#define s second
 
const ll inf=1e18;
 
int a[1000005],b[1000005],pos[1000005],pos2[1000005];
ll dp[2][1000005],qs[1000005];
 
ll f(int L,int R){
    int x=pos2[L];
    if(x>R) return 0;
    return qs[R]-qs[x-1]-L*(R-x+1);
}
 
void play2(int n,bool z){
    for(int i=1;i<=n;++i){
        dp[z][i]=inf;
        for(int j=0;j<i;++j){
            if(pos2[j+1]>i){
                dp[z][i]=min(dp[z][i],dp[!z][j]);
                break;
            }
            dp[z][i]=min(dp[z][i],-j*i+dp[!z][j]-qs[pos2[j+1]-1]+1LL*pos2[j+1]*(j+1)-j+qs[i]-i-1);
        }
    }
}
 
void play(int l,int r,int optl,int optr,int z){
    if(l>r) return;
    int mid=l+r>>1;
    pair<ll,int> best(inf,0);
    for(int i=optl;i<=min(mid,optr);++i){
        best=min(best,{dp[!z][i-1]+f(i,mid),i});
    }
    dp[z][mid]=best.f;
    play(l,mid-1,optl,best.s,z);
    play(mid+1,r,best.s,optr,z);
}
 
int main(){
    ios::sync_with_stdio(false); cin.tie(0);
 
    int n,K; cin>>n>>K;
    string s; cin>>s;
    for(int i=0,ia=0,ib=0;i<s.length();++i){
        if(s[i]=='A') a[++ia]=i;
        else b[++ib]=i;
    }
    for(int i=1,j=1;i<=n;++i){
        while(j<=n&&b[j]<a[i]) ++j;
        pos[i]=j;
        qs[i]=qs[i-1]+j;
    }
    for(int i=1,j=1;i<=n;++i){
        while(j<=n&&pos[j]<=i) ++j;
        j=max(i,j);
        pos2[i]=j;
    }
    for(int i=1;i<=n;++i) dp[1][i]=qs[i]-i;
    for(int k=2;k<=K;++k){
        // play(1,n,1,n,k&1);
        play2(n,k&1);
    }
    cout<<dp[K&1][n]<<endl;
 
    return 0;
}

Compilation message (stderr)

chorus.cpp: In function 'void play(int, int, int, int, int)':
chorus.cpp:34:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   34 |     int mid=l+r>>1;
      |             ~^~
chorus.cpp: In function 'int main()':
chorus.cpp:49:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   49 |     for(int i=0,ia=0,ib=0;i<s.length();++i){
      |                           ~^~~~~~~~~~~

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