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python/TangDou/LuoGuBook/P1029_2.cpp
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2025-08-30 18:35:01 +08:00

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#include <bits/stdc++.h>
using namespace std;
//最大公约数
int gcd(int x, int y) {
return y ? gcd(y, x % y) : x;
}
//最小公倍数
int lcm(int x, int y) {
return y / gcd(x, y) * x; //注意顺序,防止乘法爆int
}
int cnt;
int x; //最大公约数
int y; //最小公倍数
int main() {
//利用性质4:gcd(p,q)*lcm(p,q)=p*q
//可以减少一维循环
cin >> x >> y;
for (int p = x; p <= y; p++) { //穷举进化法
int q = x * y / p; //已知p,通过性质最大公约*最小公倍=两个数的乘积,
// 可以计算出另一个数字,这样,就可以去掉一层循环,效率明显提升。
// 应该满足如下的要求
if (gcd(p, q) == x && lcm(p, q) == y) cnt++;
}
cout << cnt << endl;
return 0;
}