51nod1022 石子归并 V2

#include<cstdio>
#include<cstring>
#include<cctype>
#include<algorithm>
using namespace std;
#define rep(i,s,t) for(int i=s;i<=t;i++)
#define dwn(i,s,t) for(int i=s;i>=t;i--)
#define clr(x,c) memset(x,c,sizeof(x))
#define ll long long
int read(){
	int x=0;char c=getchar();
	while(!isdigit(c)) c=getchar();
	while(isdigit(c)) x=x*10+c-‘0‘,c=getchar();
	return x;
}
const int nmax=2e3+5;
const ll inf=1e17;
ll a[nmax],dp[nmax][nmax],s[nmax][nmax];
void mins(ll &a,ll b){
	if(a>b) a=b;
}
int main(){
	int n=read();rep(i,1,n*2) rep(j,1,n*2) dp[i][j]=inf;
	rep(i,1,n) a[i]=read();
	rep(i,1,n) a[i+n]=a[i];
	rep(i,1,2*n) a[i]+=a[i-1],dp[i][i]=0,s[i][i]=i;
	int t,tp;
	rep(i,1,n-1) rep(j,1,2*n-i) {
		t=j+i;
		rep(k,s[j][t-1],s[j+1][t]) {
			tp=dp[j][k]+dp[k+1][t]+a[t]-a[j-1];
			if(tp<dp[j][t]) dp[j][t]=tp,s[j][t]=k;
		}
	}
	ll ans=inf;
	rep(i,1,n) mins(ans,dp[i][i+n-1]);
	printf("%lld\n",ans);
	return 0;
}