1 #include <stdio.h>
2 int d[100005][50];
3 int max(int a,int b)
4 {
5 if (a>b) return(a);
6 return(b);
7 }
8 int rmq(int l,int r)
9 {
10 int k=0;
11 while ((1<<(k+1))<=r-l+1) k++;
12 return(max(d[l][k],d[r-(1<<k)+1][k]));
13 }
14 int main()
15 {
16 int a[100005],k,n,i,j,p,q,x,y,sum,count[100005],num[100005],right[100005],left[100005];
17 while (~scanf("%d",&n)&&n!=0)
18 {
19 scanf("%d",&k);
20 for (i=1;i<=n;i++) scanf("%d",&a[i]);
21 a[0]=1000001; sum=0;
22 for (i=1;i<=n;i++)
23 if (a[i]==a[i-1])
24 {
25 count[sum]++;
26 num[i]=sum;
27 }
28 else
29 {
30 right[sum]=i-1;
31 sum++;
32 left[sum]=i;
33 count[sum]=1;
34 num[i]=sum;
35 }
36 right[sum]=n;
37
38 for (i=1;i<=sum;i++) d[i][0]=count[i];
39 for (j=1;(1<<j)<=sum;j++)
40 for (i=1;i+(1<<j)-1<=sum;i++)
41 d[i][j]=max(d[i][j-1],d[i+(1<<(j-1))][j-1]);
42
43 for (i=1;i<=k;i++)
44 {
45 scanf("%d%d",&p,&q);
46 if (num[p]==num[q]) {printf("%d\n",q-p+1);continue;}
47 x=max(right[num[p]]-p+1,q-left[num[q]]+1);
48 if (right[num[p]]+1==left[num[q]]) y=0; else
49 y=rmq(num[p]+1,num[q]-1);
50 printf("%d\n",max(x,y));
51 }
52 }
53 return(0);
54 }
http://acm.hdu.edu.cn/showproblem.php?pid=1806
