POJ 3368 Frequent values(RMQ 求区间出现最多次数的数字的次数)

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题目链接:http://poj.org/problem?

id=3368


Description

You are given a sequence of n integers a1 , a2 , ... , an 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 ai , ... , aj.

Input

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 , ... , an (-100000 ≤ ai ≤ 100000, for each i ∈ {1, ..., n}) separated by spaces. You can assume that for each i ∈ {1, ..., n-1}: ai ≤ ai+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

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

Source


PS:

RMQ介绍+模板:http://blog.csdn.net/u012860063/article/details/40752197

代码例如以下:

#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;

const int maxn = 100017;
int num[maxn], f[maxn], MAX[maxn][20];
int n;
int max(int a,int b)
{
    return a>b ?

a:b; } int rmq_max(int l,int r) { if(l > r) return 0; int k = log((double)(r-l+1))/log(2.0); return max(MAX[l][k],MAX[r-(1<<k)+1][k]); } void init() { for(int i = 1; i <= n; i++) { MAX[i][0] = f[i]; } int k = log((double)(n+1))/log(2.0); for(int i = 1; i <= k; i++) { for(int j = 1; j+(1<<i)-1 <= n; j++) { MAX[j][i] = max(MAX[j][i-1],MAX[j+(1<<(i-1))][i-1]); } } } int main() { int a, b, q; while(scanf("%d",&n) && n) { scanf("%d",&q); for(int i = 1; i <= n; i++) { scanf("%d",&num[i]); } sort(num+1,num+n+1); for(int i = 1; i <= n; i++) { if(i == 1) { f[i] = 1; continue; } if(num[i] == num[i-1]) { f[i] = f[i-1]+1; } else { f[i] = 1; } } init(); for(int i = 1; i <= q; i++) { scanf("%d%d",&a,&b); int t = a; while(t<=b && num[t]==num[t-1]) { t++; } int cnt = rmq_max(t,b); int ans = max(t-a,cnt); printf("%d\n",ans); } } return 0; } /* 10 3 -1 -1 1 2 1 1 1 10 10 10 2 3 1 10 5 10 */



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