P1102 A-B数对

P1102 A-B数对
用map过掉，可以当高效的桶排用，map<long long,int>m;
意思是m[long long]==int;

#include<iostream>
#include<cstdio>
#include<queue>
#include<algorithm>
#include<cmath>
#include<map>
#include<ctime>
#include<cstring>
#define inf 2147483647
#define For(i,a,b) for(register long long i=a;i<=b;i++)
#define p(a) putchar(a)
#define g() getchar()
//by war
//2017.10.13
using namespace std;
long long n,c,ans;
long long a[200010];
map<long long,int>m;
void in(long long &x)
{
    long long y=1;
    char c=g();x=0;
    while(c<'0'||c>'9')
    {
    if(c=='-')
    y=-1;
    c=g();
    }
    while(c<='9'&&c>='0')x=x*10+c-'0',c=g();
    x*=y;
}
void o(long long x)
{
    if(x<0)
    {
        p('-');
        x=-x;
    }
    if(x>9)o(x/10);
    p(x%10+'0');
}

long long find(long long x)
{
    long long l=x,r=n,mid;
    while(l<r)
    {
        mid=(l+r)>>1;
        if(a[mid]>=a[x]+c)
        r=mid;
        else
        l=mid+1;
    }
    return l-1;
}

int main()
{
    in(n),in(c);
    For(i,1,n)
    in(a[i]),m[a[i]]++;
    sort(a+1,a+n+1);
    For(i,1,n)
    ans+=m[a[i]-c];    
    o(ans);
     return 0;
}