H - Frequent values

Problem F: Frequent values

You are given a sequence of n integers a₁ , a₂ , ... , a_n in non-decreasing order. In addition to that, you are given several queries consisting of indices i and j (1 ≤ i ≤ j ≤ n). For each query, determine the most frequent value among the integers a_i , ... , a_j.

Input Specification

The input consists of several test cases. Each test case starts with a line containing two integers n and q (1 ≤ n, q ≤ 100000). The next line contains n integers a₁ , ... , a_n (-100000 ≤ a_i ≤ 100000, for each i ∈ {1, ..., n}) separated by spaces. You can assume that for each i ∈ {1, ..., n-1}: a_i ≤ a_i+1. The following q lines contain one query each, consisting of two integers i and j (1 ≤ i ≤ j ≤ n), which indicate the boundary indices for the query.

The last test case is followed by a line containing a single 0.

Output Specification

For each query, print one line with one integer: The number of occurrences of the most frequent value within the given range.

Sample Input

10 3
-1 -1 1 1 1 1 3 10 10 10
2 3
1 10
5 10
0

Sample Output

1
4
3

RMQ问题

 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <cmath>
 #include <algorithm>
 #include <string>
 #include <vector>
 #include <stack>
 #include <queue>
 #include <set>
 #include <map>
 #include <list>
 #include <iomanip>
 #include <cstdlib>
 #include <sstream>
 using namespace std;
 typedef long long LL;
 const int INF=0x5fffffff;
 const double EXP=1e-;
 const int MS=;

 int dp[MS][];
 int a[MS],cnt[MS];
 int num[MS],l[MS],r[MS];
 int n,q;

 void RMQ_init()
 {
     for(int i=;i<n;i++)
         dp[i][]=cnt[i];
     for(int j=;(<<j)<=n;j++)
     {
         for(int i=;i+(<<j)-<n;i++)
             dp[i][j]=max(dp[i][j-],dp[i+(<<(j-))][j-]);
     }
 }

 int RMQ(int l,int r)
 {
     int k=;
     while(<<(k+)<=r-l+)
         k++;
     return max(dp[l][k],dp[r-(<<k)+][k]);
 }

 int main()
 {
     while(scanf("%d%d",&n,&q)==&&n)
     {
         for(int i=;i<n;i++)
             scanf("%d",&a[i]);
         a[n]=a[n-]+;
         int start=;
         int id=;
         for(int i=;i<=n;i++)
         {
             if(i>&&a[i]>a[i-])
             {
                 for(int j=start;j<i;j++)
                     r[j]=i-;
                 cnt[id]=i-start;
                 id++;
                 start=i;
             }
             l[i]=start;
             num[i]=id;
         }
         n=id;
         RMQ_init();
         int x,y;
         while(q--)
         {
             scanf("%d%d",&x,&y);
             x--;
             y--;
             int ans=;
             if(num[x]==num[y])
             {
                 printf("%d\n",y-x+);
                 continue;
             }
             ans=max(r[x]-x+,y-l[y]+);
             if(num[x]+<num[y])
                 ans=max(ans,RMQ(num[x]+,num[y]-));
             printf("%d\n",ans);
         }

     }
     return ;
 }