hdu 3480 Division

dp+斜率优化~~

http://acm.hdu.edu.cn/showproblem.php?pid=3480

View Code

 1 # include<stdio.h>

 2 # include<string.h>

 3 # include<stdlib.h>

 4 # define N 10005

 5 int a[N],s[N],k;

 6 int dp[2][N];

 7 int cmp(const void *a,const void *b)

 8 {

 9     return *(int *)a -*(int *)b;

10 }

11 int K(int i1,int i2,int j)

12 {

13     int x1,y1,x2,y2,x0,y0;

14     y1=dp[(k-1)%2][i1]+a[i1+1]*a[i1+1];

15     x1=a[i1+1];

16     y2=dp[(k-1)%2][i2]+a[i2+1]*a[i2+1];

17     x2=a[i2+1];

18     y0=dp[(k-1)%2][j]+a[j+1]*a[j+1];

19     x0=a[j+1];

20     return (x2-x1)*(y0-y2)-(x0-x2)*(y2-y1);

21 }

22 int G(int j,int i)

23 {

24     return dp[(k-1)%2][j]+(a[j+1]-a[i])*(a[j+1]-a[i]);

25 }

26 int main()

27 {

28     int i,j,n,m;

29     int t,ncase;

30     int f,end,mm;

31     scanf("%d",&ncase);

32     for(t=1;t<=ncase;t++)

33     {

34         scanf("%d%d",&n,&m);

35         for(i=1;i<=n;i++)

36             scanf("%d",&a[i]);

37         printf("Case %d: ",t);

38         if(n<=m) {printf("0\n");continue;}

39         memset(dp,0,sizeof(dp));

40         qsort(a+1,n,sizeof(a[1]),cmp);

41         mm=1;

42         for(i=2;i<=n;i++)

43             if(a[i]!=a[i-1]) a[++mm]=a[i];

44         n=mm;

45         for(i=1;i<=n;i++)

46             dp[1][i]=(a[i]-a[1])*(a[i]-a[1]);

47         for(k=2;k<=m;k++)

48         {

49             f=1;

50             end=0;

51             for(i=k;i<=n;i++)

52             {

53                 j=i-1;

54                 while(end-1>=f && K(s[end-1],s[end],j)<=0) end--;

55                 s[++end]=j;

56                 while(f<end && G(s[f],i)>=G(s[f+1],i)) f++;

57                 dp[k%2][i]=G(s[f],i);

58             }

59         }

60         printf("%d\n",dp[m%2][n]);

61     }

62     return 0;

63 }