Polygon POJ - 1179

 

 

 除了维护一个区间最大值，还要一个最小值，( 有负数)

 

 

#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std ;
 const int N=160;
 
 #define inf 1e9
 int n,a[N],f[N][N],g[N][N];
 char op[N] ;
 
 
 signed main(){
 	 int i,j,k;
 	 cin>>n;
 	 for(i=1;i<=n;i++){
 	 	cin>>op[i]>>a[i],a[i+n]=a[i],op[i+n]=op[i];
 	 }
 	 for(i=1;i<=n*2;i++)
 	  for(j=1;j<=n*2;j++) f[i][j]=-inf,g[i][j]=inf;
 	 for(i=1;i<=n*2;i++) f[i][i]=g[i][i]= a[i];
 	 
 	 for(int len=2;len<=n;len++)
 	  for(i=1;i+len-1<=2*n;i++){
 	  	j=i+len-1;
 	  	for(k=i;k<j;k++){
 	  		if(op[k+1]=='t'){
 	  			f[i][j]= max(f[i][j],f[i][k]+f[k+1][j]);
 	  			g[i][j]= min(g[i][j], g[i][k]+g[k+1][j]);
 	  		}
 	  		else{
 	  			f[i][j]=max(f[i][j],max(f[i][k]*f[k+1][j],
 	  			max(f[i][k]*g[k+1][j],max(g[i][k]*f[k+1][j],
 	  			g[i][k]*g[k+1][j]))));
 	  			
 	  			g[i][j]=min(g[i][j],min(f[i][k]*f[k+1][j],
 	  			min(f[i][k]*g[k+1][j],min(g[i][k]*f[k+1][j],
 	  			g[i][k]*g[k+1][j]))));
 	  		}
 	  	}
 	  }
 	  int ans= -inf;
 	  for(i=1;i<=n;i++)  ans=max(ans,f[i][i+n-1]);
 	  cout<<ans<<endl;
 	  for(i=1;i<=n;i++) if(f[i][i+n-1]==ans) cout<<i<<' ';
 }