【填坑向】bzoj2038小Z的袜子 莫队

#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;
int n,m,N,c[50001],a[50001];
long long ans[50001],an[50001];
struct que{int l,r,id;}q[50001];
bool operator<(que a,que b){return ((a.l/N)<(b.l/N)) || ((a.l/N==b.l/n)&&(a.r/N<b.r/N));}
long long gcd(long long a,long long b)
{
if(b==0)    return a;
else    return(gcd(b,a%b));
}
int main()
{
scanf("%d%d",&n,&m);N=(int)sqrt(n);
for(int i=1;i<=n;i++)
scanf("%d",&c[i]);
for(int i=1;i<=m;i++)
scanf("%d%d",&q[i].l,&q[i].r),q[i].id=i;
sort(q+1,q+m+1);
int l=q[1].l,r=q[1].l;long long s=0;
a[c[l]]=1;
for(int i=1;i<=m;i++)
{
while(l>q[i].l)    s+=a[c[--l]],a[c[l]]++;
while(l<q[i].l)    a[c[l]]--,s-=a[c[l++]];
while(r<q[i].r)    s+=a[c[++r]],a[c[r]]++;
while(r>q[i].r)    a[c[r]]--,s-=a[c[r--]];
ans[q[i].id]=s;an[q[i].id]=(long long)(q[i].r-q[i].l)*(q[i].r-q[i].l+1)/2;
}
for(int i=1;i<=m;i++)
printf("%lld/%lld\n",ans[i]/gcd(an[i],ans[i]),an[i]/gcd(an[i],ans[i]));
return 0;
}