题目分析:
- 转换问题, A=B+C,查找 (b+C)=A出现的次数
Code:
#include <bits/stdc++.h>
using namespace std;
#define maxn 200010
int n,c,maxd=0,a[maxn];
inline int read_() {
int x=0,f=1;
char c=getchar();
while(c<'0'||c>'9') {
if(c=='-') f=-1;
c=getchar();
}
while(c>='0'&&c<='9') {
x=(x<<1)+(x<<3)+c-'0';
c=getchar();
}
return x*f;
}
void readda_() {
n=read_();c=read_();
for(int i=1;i<=n;++i) {
a[i]=read_();
}
sort(a+1,a+n+1);
long long ans=0;
for(int i=1;i<=n;++i) {
ans+=upper_bound(a+1,a+n+1,a[i]+c)-lower_bound(a+1,a+n+1,a[i]+c);
}
printf("%lld",ans);
}
int main() {
freopen("a.txt","r",stdin);
readda_();
return 0;
}