UVA 11235 Frequent values

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 using namespace std;
 5 
 6 const int maxn=100005;
 7 
 8 int count[maxn];
 9 int num[maxn],ll[maxn],rr[maxn];
10 int tot;
11 int d[maxn][50];
12 
13 int rmq (int l,int r){
14     int k=0;
15     while ( (1<<(k+1)) <= r-l+1 ) k++;
16     return max(d[l][k],d[r-(1<<k)+1][k]);
17 }
18 
19 int main (){
20     int n,q;
21     while (cin>>n&&n){
22         cin>>q;
23         tot=0;
24         memset (count,0,sizeof count);
25         int temp=99999999;
26         ll[tot]=0;
27         for (int i=1;i<=n;i++){
28             int x;
29             cin>>x;
30             if (x!=temp){
31                 temp=x;
32                 rr[tot]=i-1;
33                 tot++;
34                 ll[tot]=i;
35             }
36             count[tot]++;
37             num[i]=tot;
38         }
39         rr[tot]=n;
40         for (int i=1;i<=tot;i++) d[i][0]=count[i];//cout<<count[i]<<" ";cout<<endl;
41         for (int j=1;(1<<j)<=tot;j++){
42             for (int i=1;i+(1<<(j-1))<=tot;i++){
43                 d[i][j]=max (d[i][j-1],d[i+(1<<(j-1))][j-1]);
44             }
45         }
46         while (q--){
47             int l,r;
48             cin>>l>>r;
49             int ans=0;
50             if (num[l]==num[r]){
51                 cout<<r-l+1<<endl;
52                 continue ;
53             }
54             //if (rr[num[l]]<=r)
55                 ans=max (ans,rr[num[l]]-l+1);
56             //if (ll[num[r]]>=l)
57                 ans=max (ans,r-ll[num[r]]+1);//cout<<num[l]+1<<" "<<num[r]-1<<"err"<<endl;
58             if (num[l]+1<=num[r]-1)
59                 ans=max (ans,rmq (num[l]+1,num[r]-1));//cout<<rmq (num[l]+1,num[r]-1)<<"aaa"<<endl;
60             cout<<ans<<endl;
61         }
62     }
63     return 0;
64 }