JSOI2009 BZOJ2257 瓶子和燃料

#include <cstdio>
#include <iostream>

using namespace std;

long a[1001];
long s[1000001];

long gcd(long a,long b){
if (a%b==0) {
return b;
}
if (b%a==0) {
return a;
}
return gcd(b,a%b);
}
void qqsort(long l,long r){
long i=l,j=r,x;
x=s[(l+r)/2];
/*cout <<l <<" " <<r <<endl;*/
long t;
while (i<=j){
while (s[i]<x){
i++;
}
while (x<s[j]){
j--;
}
if (i<=j){
t=s[i];s[i]=s[j];s[j]=t;
i++;j--;
}
}
if (i<r){
qqsort(i,r);
}
if (j>l){
qqsort(l,j);
}
}

int main(){
/*freopen("bottle.in", "r", stdin) ;
freopen("bottle.out", "w", stdout) ;*/
long n,k;
cin >>n >>k;
for (long i=1;i<=n;i++){
cin>>a[i];
}
long r=0;
for (long i=1;i<=n;i++){
for (long j=1;j*j<=a[i];j++){
if (a[i]%j==0){
r++;s[r]=j;
//cout <<s[r] <<endl;
r++;s[r]=a[i]/j;
//cout <<s[r] <<endl;
}
}
}
qqsort(1,r);
long app=1;
for (long i=r-1;i>0;i--){
if (s[i]==s[i+1]){
app++;
}
else
{
app=1;
}
if (app>=k){
cout <<s[i] <<endl;
break;
}
}
/*cin >>n;*/
}