HDU 6534 莫队+树状数组 奇偶优化

http://acm.hdu.edu.cn/showproblem.php?pid=6534

 

题意：l,r区间内差值小于k的对数

 

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 27005;
int n,m,k;
int a[maxn];
int b[maxn];
int len;
struct node{
	int l,r;
	int x;
	int id;
	int ans;
	bool operator<(const node &a) const {
        if (l / len == a.l / len)
            return (l / len) & 1 ? r < a.r : r > a.r;
        return l / len < a.l / len;
    }
} c[maxn];
int pos[maxn];
int d[maxn]; 
vector<int> v;
int ans;
int nn;
bool cmp1(node x,node y){
	if(pos[x.l]==pos[y.l])
	{
		if(x.r<y.r)
			return true;
		return false;
	 } 
	if(x.l<y.l)
		return true;
	return false;
}
bool cmp2(node x,node y){
	return x.id<y.id;
}
int lowbit(int x)
{
    
    return x&(-x);    
} 
int Query(int x)
{
    int aa = 0 ;
    while(x)
    {
    	aa += d[x];
    	x -= lowbit(x);
    } 
    return aa;
}
void add(int x ,int value)
{
	int tnt = a[x]+k;
	int tnc = upper_bound(v.begin(),v.end(),tnt)-v.begin()-1;
	int cnt = max(a[x]-k,0);
	int cnc;
	if(cnt!=0)
		cnc = lower_bound(v.begin(),v.end(),cnt)-v.begin()-1;
	else
		cnc = 0;
	ans += Query(tnc)-Query(cnc);
//	cout<<Query(tnc)<<" "<<Query(cnc)<<endl;
//	cout<<tnt<<" "<<cnt<<" "<<tnc<<" "<<cnc<<" "<<ans<<endl; 
	
	x = b[x];
    while(x<=nn)
    {
        d[x] += value;
        x += lowbit(x);
    }
}
void remove(int x ,int value)
{
	int tnt = a[x]+k;
	int tnc = upper_bound(v.begin(),v.end(),tnt)-v.begin()-1;
	int cnt = max(a[x]-k,0);
	int cnc;
	if(cnt!=0)
		cnc = lower_bound(v.begin(),v.end(),cnt)-v.begin()-1;
	else
		cnc = 0;
	ans -= Query(tnc)-Query(cnc)-1;
//	cout<<Query(tnc)<<" "<<Query(cnc)<<endl;
//	cout<<tnt<<" "<<cnt<<" "<<tnc<<" "<<cnc<<" "<<ans<<endl; 
	
	x = b[x];
//	cout<<d[x]<<endl;
    while(x<=nn)
    {
        d[x] += value;
//        cout<<d[x]<<endl;
        x += lowbit(x);
    }
}
int main()
{
	cin>>n>>m>>k; 
	memset(d,0,sizeof(d));
	v.push_back(0);
	for(int i=1;i<=n;i++)
		cin>>a[i],v.push_back(a[i]);
	sort(v.begin(),v.end());
	v.erase(unique(v.begin(),v.end()),v.end());
	nn = v.size();
	for(int i=1;i<=n;i++)
		b[i] = lower_bound(v.begin(),v.end(),a[i])-v.begin();
	for(int i=1;i<=m;i++)
	{
		cin>>c[i].l>>c[i].r;
		c[i].x = i;
		c[i].id = i;
	}
	len = sqrt(n);
	for(int i=1;i<=m;i++)
		pos[i] = (i-1)/len + 1;
	sort(c+1,c+1+m);
//	cout<<endl;
//	for(int i=1;i<=m;i++)
//		cout<<c[i].l<<" "<<c[i].r<<endl;
//	cout<<endl;
	int l = 1,r = 0 ;
	ans = 0;
	for(int i=1;i<=m;i++)
	{
		while(r<c[i].r)
		{
			r++;
			add(r,1);
		}
		while(r>c[i].r)
		{
			remove(r,-1);
			r--;
		}
		while(l<c[i].l)
		{
			remove(l,-1);
			l++;
		}
		while(l>c[i].l)
		{
			l--;
			add(l,1);
		}
		c[i].ans = ans;
	}
	sort(c+1,c+1+m,cmp2);
	for(int i=1;i<=m;i++)
		cout<<c[i].ans<<endl;
	return 0;
}