记录编号	337864	评测结果	AAAAAAAAAAAAAAAAAAAA
题目名称	__卡片游戏	最终得分	100
用户昵称	Sky_miner	是否通过	通过
代码语言	C++	运行时间	4.399 s
提交时间	2016-11-04 21:44:18	内存使用	19.72 MiB

#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
typedef long long ll;
inline void read(ll &x){
	x=0;char ch;bool flag = false;
	while(ch=getchar(),ch<'!');if(ch == '-') ch=getchar(),flag = true;
	while(x=10*x+ch-'0',ch=getchar(),ch>'!');if(flag) x=-x;
}
inline ll cat_max(const ll &a,const ll &b){return a>b ? a:b;}
inline ll cat_min(const ll &a,const ll &b){return a<b ? a:b;}
const ll maxn = 500010;
ll gcd(const ll &a,const ll &b){return b == 0 ? a : gcd(b,a%b);}
ll c[maxn];
ll sum1[maxn],sum2[maxn];
ll t1[maxn],t2[maxn],n;
#define lowbit(x) x&-x
ll C[maxn];
inline ll query(ll i){
	ll ret = 0;
	for(ll x = i;x;x-=lowbit(x)) ret += C[x];
	return ret;
}
inline void add(ll i){
	for(ll x = i;x<=n;x+=lowbit(x)) ++C[x];
}
int main(){
	freopen("xgame.in","r",stdin);
	freopen("xgame.out","w",stdout);
	ll l,r;read(n);read(l);read(r);
	for(ll i=1;i<=n;++i) read(c[i]);
	for(ll i=1;i<=n;++i){
		sum1[i] = sum1[i-1] + c[i] - l;
		sum2[i] = sum2[i-1] + c[i] - r;
		t1[i] = sum1[i];t2[i] = sum2[i];
	}sort(t1+1,t1+n+2);sort(t2+1,t2+n+2);
	for(ll i=0;i<=n;++i){
		sum1[i] = lower_bound(t1+1,t1+n+2,sum1[i]) - t1;
		sum2[i] = lower_bound(t2+1,t2+n+2,sum2[i]) - t2;
	}
	ll m = (n*(n+1))>>1;
	ll ans = 0;
	//puts("");
	add(sum1[0]);
	for(ll i=1;i<=n;++i){
		ans += i - query(sum1[i]);
		add(sum1[i]);
	}
	memset(C,0,sizeof C);
	add(sum2[0]);
	for(ll i=1;i<=n;++i){
		ans += query(sum2[i] - 1) ;
		add(sum2[i]);
	}
	ans = m - ans;
	ll x = gcd(ans,m);
	m /= x;ans /= x;
	if(ans == 0) printf("0");
	else if(m == ans) printf("1");
	else printf("%lld/%lld",ans,m);
	getchar();getchar();
	return 0;
}