【HDOJ】【3506】Monkey Party

DP/四边形不等式

---

　　裸题环形石子合并……

　　拆环为链即可

 //HDOJ 3506
 #include<cmath>
 #include<vector>
 #include<cstdio>
 #include<cstring>
 #include<cstdlib>
 #include<iostream>
 #include<algorithm>
 #define rep(i,n) for(int i=0;i<n;++i)
 #define F(i,j,n) for(int i=j;i<=n;++i)
 #define D(i,j,n) for(int i=j;i>=n;--i)
 #define pb push_back
 #define CC(a,b) memset(a,b,sizeof(a))
 using namespace std;
 int getint(){
     int v=,sign=; char ch=getchar();
     while(!isdigit(ch)) {if(ch=='-') sign=-; ch=getchar();}
     while(isdigit(ch))  {v=v*+ch-''; ch=getchar();}
     return v*sign;
 }
 const int N=;
 const int INF=;
 const double eps=1e-;
 /*******************template********************/
 int s[N][N],a[N];
 int dp[N][N];
 int main(){
 #ifndef ONLINE_JUDGE
     freopen("input.txt","r",stdin);
 //    freopen("output.txt","w",stdout);
 #endif
     int n;
     while(scanf("%d",&n)!=EOF && n){
         CC(a,);CC(s,);
         F(i,,n) a[i+n]=a[i]=getint();
         F(i,,n<<) a[i]+=a[i-];
         F(i,,n*-){
             dp[i][i+]=a[i+]-a[i-];
             s[i][i+]=i;
         }
         F(len,,n)
             F(i,,n*-len+){
                 int j=i+len-;
                 dp[i][j]=INF;
                 F(k,s[i][j-],s[i+][j]){
                     int tmp=dp[i][k]+dp[k+][j]+a[j]-a[i-];
                     if (tmp<dp[i][j]){
                         dp[i][j]=tmp;
                         s[i][j]=k;
                     }
                 }
             }
         int ans=INF;
         F(i,,n) ans=min(ans,dp[i][i+n-]);
         printf("%d\n",ans);
     }
     return ;
 }