HDU4638:Group(线段树离线处理)

最新推荐文章于 2019-04-15 22:11:48 发布

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最新推荐文章于 2019-04-15 22:11:48 发布

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分类专栏：线段树文章标签： HDU

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本文介绍了一种优化算法，用于处理查询区间内将连续数列分组以最大化值的问题。通过离线处理所有查询并使用树状数组进行高效计算，实现了对输入数组的快速分析。

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Problem Description

There are n men ,every man has an ID(1..n).their ID is unique. Whose ID is i and i-1 are friends, Whose ID is i and i+1 are friends. These n men stand in line. Now we select an interval of men to make some group. K men in a group can create K*K value. The value of an interval is sum of these value of groups. The people of same group's id must be continuous. Now we chose an interval of men and want to know there should be how many groups so the value of interval is max.

Input

First line is T indicate the case number.
For each case first line is n, m(1<=n ,m<=100000) indicate there are n men and m query.
Then a line have n number indicate the ID of men from left to right.
Next m line each line has two number L,R(1<=L<=R<=n),mean we want to know the answer of [L,R].

Output

For every query output a number indicate there should be how many group so that the sum of value is max.

Sample Input

Sample Output

1
2


题意：给出一个数组，每次查询l,r，看区间内能分成几个连续的数列

思路：离线处理所有查询

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <vector>
#include <math.h>
#include <bitset>
#include <algorithm>
#include <climits>
using namespace std;

#define ls 2*i
#define rs 2*i+1
#define UP(i,x,y) for(i=x;i<=y;i++)
#define DOWN(i,x,y) for(i=x;i>=y;i--)
#define MEM(a,x) memset(a,x,sizeof(a))
#define W(a) while(a)
#define gcd(a,b) __gcd(a,b)
#define LL long long
#define N 100005
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define EXP 1e-8
#define rank rank1
const int mod = 10007;

struct node
{
    int l,r,val;
} a[N*4],s[N];

int num[N],pos[N],vis[N],ans[N];
int n,m;

int cmp(node a,node b)
{
    return a.r<b.r;
}

void build(int l,int r,int i)
{
    a[i].l = l;
    a[i].r = r;
    a[i].val = 0;
    if(l==r) return;
    int mid = (l+r)/2;
    build(l,mid,ls);
    build(mid+1,r,rs);
}

void updata(int i,int pos,int v)
{
    a[i].val+=v;
    if(a[i].l==a[i].r) return;
    int mid = (a[i].l+a[i].r)/2;
    if(pos<=mid) updata(ls,pos,v);
    else updata(rs,pos,v);
}

int query(int l,int r,int i)
{
    if(a[i].l==l&&a[i].r==r)
    {
        return a[i].val;
    }
    int mid = (a[i].l+a[i].r)/2;
    if(r<=mid) return query(l,r,ls);
    if(l>mid) return query(l,r,rs);
    return query(l,mid,ls)+query(mid+1,r,rs);
}

int main()
{
    int t,i,j,k,cnt;
    scanf("%d",&t);
    while(t--)
    {
        MEM(vis,0);
        scanf("%d%d",&n,&m);
        for(i = 1; i<=n; i++)
        {
            scanf("%d",&num[i]);
            pos[num[i]] = i;
        }
        for(i = 1; i<=m; i++)
        {
            scanf("%d%d",&s[i].l,&s[i].r);
            s[i].val = i;
        }
        sort(s+1,s+1+m,cmp);
        build(1,n,1);
        cnt = 1;
        for(i = 1; i<=n&&cnt<=m; i++)
        {
            updata(1,i,1);
            vis[num[i]]=1;
            if(vis[num[i]-1]) updata(1,pos[num[i]-1],-1);
            if(vis[num[i]+1]) updata(1,pos[num[i]+1],-1);
            while(s[cnt].r==i&&cnt<=m)
            {
                ans[s[cnt].val] = query(s[cnt].l,s[cnt].r,1);
                cnt++;
            }
        }
        for(i = 1; i<=m; i++)
            printf("%d\n",ans[i]);
    }

    return 0;
}