Frequent values-------最多的连续的个数

最新推荐文章于 2021-04-10 14:46:54 发布

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最新推荐文章于 2021-04-10 14:46:54 发布

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分类专栏：数据结构——线段树

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给定一个非递减顺序的整数序列，你需要处理一些查询，每个查询包含两个索引i和j。对于每个查询，找出范围[i, j]内的最常出现的数值。" 133106443,20036795,Linux进程内存布局与单片机内存管理,"['Linux', '单片机', '内存管理']

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Frequent values

Time Limit : 4000/2000ms (Java/Other) Memory Limit : 131072/65536K (Java/Other)

Total Submission(s) : 58 Accepted Submission(s) : 22

Problem Description

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

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

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<cstring>
#include<cmath>
#define M 100001
using namespace std;
struct node
{
int l,r;
int lmax,rmax,amax;//记lmax为最左边的个数，同理
}tree[M*4];
int a[M];
void build(int id,int l,int r)
{
tree[id].l=l;
tree[id].r=r;
if(l==r)
{
tree[id].lmax=tree[id].rmax=tree[id].amax=1;
return;
}
int mid=(l+r)/2;
build(id*2,l,mid);
build(id*2+1,mid+1,r);

int count;
if(a[tree[id*2].r]==a[tree[id*2+1].l])
count=tree[id*2].rmax+tree[id*2+1].lmax;
else
count=0;
tree[id].amax=max(max(tree[id*2].amax,tree[id*2+1].amax),count);
//此时还没有更新lmax最左边数字的连续的个数，还有最右边的数字的连续的个数，所以接下来要判断
tree[id].lmax=tree[id*2].lmax;//但是此时有bug，假如左子树左右的数相同，并且与右子树左边的相等，则tree[id]就不准确了
if(tree[id*2].lmax==mid-l+1&&a[tree[id*2].r]==a[tree[id*2+1].l])
tree[id].lmax=mid-l+1+tree[id*2+1].lmax;
tree[id].rmax=tree[id*2+1].rmax;
if(tree[id*2+1].rmax==r-mid&&a[tree[id*2+1].l]==a[tree[id*2].r])//之前一直有疑问，后来想到当范围内的数全相等时，他的左右max相等
tree[id].rmax=r-mid+tree[id*2].rmax;
//build(id*2,l,mid);
//build(id*2+1,mid+1,r);

}

int query(int id,int l,int r)
{
if(tree[id].l==l&&tree[id].r==r)
return tree[id].amax;
int mid=(tree[id].l+tree[id].r)/2;
if(r<=mid)
return query(id*2,l,r);
else if(l>mid)
return query(id*2+1,l,r);
else
{
int a1=query(id*2,l,mid);
int a2=query(id*2+1,mid+1,r);
int a3=0;
if(a[tree[id*2].r]==a[tree[id*2+1].l])
{
a3=min(tree[id*2].rmax,mid-l+1)+min(tree[id*2+1].lmax,r-mid);
}
return max(max(a1,a2),a3);
}
}
int main()
{
int n;
int p;
int x,y;
while(scanf("%d",&n)!=0)
{
if(n==0)
break;
scanf("%d",&p);
for(int i=1;i<=n;i++)
{
scanf("%d",&a[i]);
}
build(1,1,n);
for(int i=0;i<p;i++)
{
scanf("%d%d",&x,&y);
cout<<query(1,x,y)<<endl;
}

}
return 0;
}