poj 3368 Frequent values

http://poj.org/problem?id=3368

 1 #include <cstdio>

 2 #include <cstring>

 3 #include <cmath>

 4 #include <algorithm>

 5 #define maxn 100100

 6 using namespace std;

 7 

 8 int a[maxn],f[maxn][30],n,q,x,y,b[maxn];

 9 

10 int main()

11 {

12     while(scanf("%d",&n)!=EOF)

13     {

14         if(n==0) break;

15         scanf("%d",&q);

16         memset(f,0,sizeof(f));

17         for(int i=1; i<=n; i++)

18         {

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

20         }

21         memset(b,0,sizeof(b));

22         for(int i=1; i<=n; i++)

23         {

24             if(i==1)

25             {

26                 b[1]=1;

27                 continue;

28             }

29             if(a[i]==a[i-1])

30             {

31                 b[i]=b[i-1]+1;

32             }

33             else

34                 b[i]=1;

35         }

36         for(int i=1; i<=n; i++)

37         {

38             f[i][0]=b[i];

39         }

40         int m=(int)(log(n*1.0)/(log(2.0)));

41         for(int j=1; j<=m; j++)

42         {

43             for(int i=1; i<=n; i++)

44             {

45                 if(i+(1<<j)-1<=n)

46                 {

47                     f[i][j]=max(f[i][j-1],f[i+(1<<(j-1))][j-1]);

48                 }

49             }

50         }

51         for(int i=0; i<q; i++)

52         {

53             scanf("%d%d",&x,&y);

54             int t=x;

55             while(t<=y&&a[t]==a[t-1])

56                 t++;

57             int k=(int)(log(y-t+1.0)/(log(2.0)));

58             int c=max(f[t][k],f[y-(1<<k)+1][k]);

59             if(t>y) c=0;

60             printf("%d\n",max(t-x,c));

61         }

62     }

63     return 0;

64 }

View Code