bzoj1484: [HNOI2009]通往城堡之路

神贪心。。。

b[i]=a[1]-(n-1)*d;

每次找价值最大的k

使b[k]~b[n]都++

#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

using namespace std;

#define maxn 6000

#define ll long long

inline long long min(long long x, long long y) {return x<y?x:y;};

inline long long max(long long x, long long y) {return x>y?x:y;};

inline long long ABS(long long x) {return x<0?-x:x;};

ll a[maxn];

ll b[maxn];

int n;

ll now=0,pp,maxx=-0x3fffffffffffffLL,jj,up=0x3fffffffffffffLL;

ll d,ans;

int m,i;

int main(){

    scanf("%d",&m);

   while(m--){

    scanf("%d%lld",&n,&d);

    for(i=1;i<=n;i++)scanf("%lld",&a[i]);

    b[1]=a[1];

    for(i=2;i<=n;i++)b[i]=b[i-1]-d;

    if(a[1]+(n-1)*d<a[n]||a[n]<a[1]-(n-1)*d){

      printf("impossible\n");  

    }else{

        ans=0;

        for(;a[n]!=b[n];){ 

            int j;

            now=0,maxx=-0x3ffffffffffffffLL,jj=0,up=0x3fffffffffffffLL;

            for( j=n;j>=2;j--){

                if(b[j]>=a[j])now--;

                else now++,up=min(up,a[j]-b[j]);   

                if(now>maxx&&b[j]<b[j-1]+d){

                  maxx=now;

                  jj=j;

                  pp=up;

                }

            }

            pp=min(pp,b[jj-1]+d-b[jj]);

            for(j=jj;j<=n;j++)b[j]+=pp;

        }

        for(i=1;i<=n;i++)ans+=ABS(b[i]-a[i]);

        printf("%lld\n",ans);

    }  

}

     

}