hdu3045 发表于 2018-10-20 | 分类于 题解 | 阅读数 次 链接:hdu3045 题解 显然根据题意排序后,所有集合都是连续的,a[i]表示每只cow的Moo~,sum前缀和,dp[i]表示前i只牛组成的集合的最小减少 即 显然是个斜率dp 1234567891011121314151617181920212223242526272829303132333435363738394041#include<iostream>#include<cstdio>#include<cstdlib>#include<cmath>#include<cstring>#include<algorithm>#define rep(i,x,y) for(register int i=x;i<=y;++i)#define repd(i,x,y) for(register int i=x;i>=y;--i)#define ll long longusing namespace std;const int N=4e5+7;template <typename T>inline void read(T &x){ char c;int sign=1;x=0; do{c=getchar();if(c=='-')sign=-1;}while(c<'0'||c>'9'); do{x=x*10+c-'0';c=getchar();}while(c>='0'&&c<='9'); x*=sign;}ll dp[N],sum[N],a[N];int n,m,q[N];inline void init(){ rep(i,1,n)read(a[i]); sort(a+1,a+n+1); rep(i,1,n)sum[i]=a[i]+sum[i-1]; rep(i,m,2*m-1)dp[i]=sum[i]-i*a[1];}inline ll Y(int x,int y){return dp[x]-sum[x]+a[x+1]*x-(dp[y]-sum[y]+a[y+1]*y);}inline ll X(int x,int y){return a[x+1]-a[y+1];}int main(){ while(~scanf("%d%d",&n,&m)){ init(); int head=1,tail=1; rep(i,2*m,n){ while(head<tail&&Y(q[tail],i-m)*X(q[tail-1],q[tail])<=Y(q[tail-1],q[tail])*X(q[tail],i-m))--tail; q[++tail]=i-m; while(head<tail&&Y(q[head+1],q[head])<=X(q[head+1],q[head])*i)++head; dp[i]=dp[q[head]]+sum[i]-sum[q[head]]-a[q[head]+1]*(i-q[head]); } printf("%I64d\n",dp[n]); } return 0;}