题解--Codeforces Round 680 [C. Division]
C. Division
Oleg's favorite subjects are History and Math, and his favorite branch of mathematics is division.
To improve his division skills, Oleg came up with \(t\) pairs of integers \(p_i\) and \(q_i\) and for each pair decided to find the greatest integer \(x_i\), such that:
- \(p_i\) is divisible by \(x_i\);
- \(x_i\) is not divisible by \(q_i\).
Oleg is really good at division and managed to find all the answers quickly, how about you?
Input
The first line contains an integer \(t\) (\(1 \le t \le 50\)) — the number of pairs.
Each of the following \(t\) lines contains two integers \(p_i\) and \(q_i\) (\(1 \le p_i \le 10^{18}\); \(2 \le q_i \le 10^{9}\)) — the \(i\)-th pair of integers.
Output
Print \(t\) integers: the \(i\)-th integer is the largest \(x_i\) such that \(p_i\) is divisible by \(x_i\), but \(x_i\) is not divisible by \(q_i\).
One can show that there is always at least one value of \(x_i\) satisfying the divisibility conditions for the given constraints.
样例
1 | 输入: |
算法1
分解质因数

参考文献
参考 #### C++ 代码 1
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using namespace std;
int t;
vector<int> div(ll x)//质因数分解
{
vector<int> res;
for(ll i=2;i*i<=x;i++)
{
if(x%i==0)
{
res.push_back(i);
while(x%i==0)
x/=i;
}
}
if(x!=1) res.push_back(x);
return res;
}
int main()
{
scanf("%d",&t);
while(t--)
{
ll p,q;
scanf("%lld%lld",&p,&q);
if(p%q!=0)
{
printf("%d\n",p);
continue;
}
vector<int >a = div(q);//获取q的所有质因数
ll res=1;
for(int i=0;i<a.size();i++)//遍历q的全部因数
{
ll k=p;
while(k%q==0)//如果剩下的数能被q整除 说明还有a[i]这个因数
{
k/=a[i];
}
res=max(res,k);
}
printf("%lld\n",res);
}
return 0;
}