noi.ac#228 book

分析

代码

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int inf =1e18;
char s[];
int a[],pre[],sur[],mn[];
signed main(){
    int n,m,p,q,i,j,k,x,y,Ans=inf;
    cin>>n>>p>>q>>x>>y;
    scanf("%s",s+);
    for(i=;i<=n;i++)a[i]=(s[i]=='-'?-:);
    for(i=;i<=n;i++)pre[i]=pre[i-]+a[i];
    for(i=;i<=n;i++)mn[i]=min(mn[i-],pre[i]);
    k=(q-p-pre[n])/;
    for(i=;i<=n;i++){
      int sum=min(pre[n]-pre[n-i+]+mn[n-i+],sur[i-]);
      int t=max(0ll,(-p-sum+)/);
      Ans=min(Ans,(abs(k-t)+t)*x+(i-)*y);
      sur[i]=min(sur[i-]+a[n-i+],0ll);
    }
    cout<<Ans;
    return ;
}