HDU 3516 Tree Construction

区间$dp$，四边形优化。

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<ctime>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0),eps=1e-;
void File()
{
    freopen("D:\\in.txt","r",stdin);
    freopen("D:\\out.txt","w",stdout);
}
template <class T>
inline void read(T &x)
{
    char c = getchar();
    x = ;
    while(!isdigit(c)) c = getchar();
    while(isdigit(c))
    {
        x = x *  + c - '';
        c = getchar();
    }
}

int n;
int x[],y[],dp[][],f[][];

int main()
{
    while(~scanf("%d",&n))
    {
        for(int i=;i<=n;i++) scanf("%d%d",&x[i],&y[i]);
        if(n==) { printf("0\n"); continue; }

        for(int i=;i<=n;i++) dp[i][i]=;
        for(int i=;i<n;i++)
        {
            dp[i][i+]=y[i]-y[i+]+x[i+]-x[i];
            f[i][i+]=i;
        }

        for(int len=;len<=n;len++)
        {
            for(int st=;st<=n&&st+len-<=n;st++)
            {
                int en=st+len-;
                dp[st][en]=0x7FFFFFFF;
                for(int j=f[st][en-];j<=f[st+][en];j++)
                {
                    if(dp[st][j]+dp[j+][en]+y[j]-y[en]+x[j+]-x[st]<dp[st][en])
                    {
                        dp[st][en]=dp[st][j]+dp[j+][en]+y[j]-y[en]+x[j+]-x[st];
                        f[st][en]=j;
                    }
                }
            }
        }

        printf("%d\n",dp[][n]);
    }
    return ;
}