luogu 4909 [Usaco2006 Mar]Ski Lift 缆车支柱 动态规划

可以出模拟赛T1?

#include <bits/stdc++.h>
#define N 5002
#define inf 1000000
#define setIO(s) freopen(s".in","r",stdin)
using namespace std;
int f[N],h[N];
double slope(int i,int j)
{
    double dx=(double)i-j;
    double dy=(double)(h[i]-h[j]);
    if(dy==0) return 0.0;
    return dy/dx;
}
int main()
{
    int i,j,n,m;
    // setIO("input");
    scanf("%d%d",&n,&m);
    for(i=1;i<N;++i) f[i]=inf;
    for(i=1;i<=n;++i) scanf("%d",&h[i]);
    f[1]=1;
    for(i=1;i<n;++i)
    {
        double pre=-100000000000.00;
        for(j=i+1;j<=n;++j)
        {
            if(j-i>m) break;
            double cur=slope(i,j);
            if(cur>=pre)
            {
                pre=max(pre, cur);
                f[j]=min(f[j], f[i]+1);
            }
        }
        // printf("%d %d\n",i,f[i]);
    }
    printf("%d\n",f[n]);
    return 0;
}