OJ-Problems-Source/HDOJ/2829_autoAC.cpp

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#include<stdio.h>
#include<iostream>
#include<string.h>
#include<algorithm>
using namespace std;
const int MAXN=1010;
int a[MAXN];
int sum[MAXN];
int cost[MAXN];
int q[MAXN];
int head,tail;
int n,m;
int dp[MAXN][MAXN];
int DP()
{
for(int i=1;i<=n;i++)
{
dp[i][0]=cost[i];
dp[i][i-1]=0;
}
for(int j=1;j<=m;j++)
{
head=tail=0;
q[tail++]=j;
for(int i=j+1;i<=n;i++)
{
while(head+1<tail)
{
int p1=q[head];
int p2=q[head+1];
int x1=sum[p1];
int x2=sum[p2];
int y1=dp[p1][j-1]-cost[p1]+sum[p1]*sum[p1];
int y2=dp[p2][j-1]-cost[p2]+sum[p2]*sum[p2];
if((y2-y1)<=sum[i]*(x2-x1)) head++;
else break;
}
int k=q[head];
dp[i][j]=dp[k][j-1]+cost[i]-cost[k]-sum[k]*sum[i]+sum[k]*sum[k];
while(head+1<tail)
{
int p1=q[tail-2];
int p2=q[tail-1];
int p3=i;
int x1=sum[p1];
int x2=sum[p2];
int x3=sum[p3];
int y1=dp[p1][j-1]-cost[p1]+sum[p1]*sum[p1];
int y2=dp[p2][j-1]-cost[p2]+sum[p2]*sum[p2];
int y3=dp[p3][j-1]-cost[p3]+sum[p3]*sum[p3];
if((y2-y1)*(x3-x2)>=(y3-y2)*(x2-x1))tail--;
else break;
}
q[tail++]=i;
}
}
return dp[n][m];
}
int main()
{
while(scanf("%d%d",&n,&m)==2)
{
if(n==0&&m==0)break;
sum[0]=0;
cost[0]=0;
for(int i=1;i<=n;i++)
{
scanf("%d",&a[i]);
sum[i]=sum[i-1]+a[i];
cost[i]=cost[i-1]+sum[i-1]*a[i];
}
printf("%d\n",DP());
}
return 0;
}