HDU5213 Lucky 莫队算法 容斥定理

#include<bits/stdc++.h>
using namespace std;
//input by bxd
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define repp(i,a,b) for(int i=(a);i>=(b);--i)
#define RI(n) scanf("%d",&(n))
#define RII(n,m) scanf("%d%d",&n,&m)
#define RIII(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define RS(s) scanf("%s",s);
#define ll long long
#define pb push_back
#define CLR(A,v)  memset(A,v,sizeof A)
#define inf 0x3f3f3f3f
#define lson l,m,pos<<1
#define rson m+1,r,pos<<1|1
//////////////////////////////////////
const int N=3e4+5;
struct node
{
    int l,r,flag,id;
}s[N<<2];

int anss[N],ans,L,R,cnt[N],n,a[N],K,m,x1,x2,y2,block,cnt1,yy;//我的cb上不能定义y1  不然疯狂报错？？？

bool judge(int x)
{
    return x>=1&&x<=n;
}
void add(int x)
{
    x=a[x];
    cnt[x]++;
    if(judge(K-x))ans+=cnt[K-x];
}
void del(int x)
{
    x=a[x];
    cnt[x]--;
    if(judge(K-x))ans-=cnt[K-x];
}
bool cmp(node a,node b)
{
    return (a.l/block)==(b.l/block)?a.r<b.r:a.l<b.l;
}
int main()
{
    while(~RI(n))
    {
        RI(K);rep(i,1,n)RI(a[i]);RI(m);cnt1=0;
        
        rep(i,1,m)
        {
            anss[i]=cnt[i]=0;
            RII(x1,yy);RII(x2,y2);
            s[++cnt1].flag=1, s[cnt1].l=x1,s[cnt1].r=y2,s[cnt1].id=i;
            s[++cnt1].flag=-1,s[cnt1].l=x1,s[cnt1].r=x2-1,s[cnt1].id=i;
            s[++cnt1].flag=-1,s[cnt1].l=yy+1,s[cnt1].r=y2,s[cnt1].id=i;
            s[++cnt1].flag=1, s[cnt1].l=yy+1,s[cnt1].r=x2-1,s[cnt1].id=i;
        }
        block=sqrt(n);
        sort(s+1,s+1+cnt1,cmp);
        L=1,R=0,ans=0;

        rep(i,1,cnt1)
        {
            int l=s[i].l,r=s[i].r;
            while(L<l)del(L++);
            while(L>l)add(--L);
            while(R<r)add(++R);
            while(R>r)del(R--);

            anss[s[i].id]+=s[i].flag*ans;
        }
        rep(i,1,m)printf("%d\n",anss[i]);
    }
    return 0;
}