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NOI Online 2022入门组 数学游戏

color_小浣熊 2022-04-01 阅读 68
c++

推导

d = gcd ⁡ ( x , y ) , x = p d , y = q d , z = p q d 3 d=\gcd(x,y),x=pd,y=qd,z=pqd^3 d=gcd(x,y),x=pd,y=qd,z=pqd3

∵ gcd ⁡ ( p , q ) = 1 \because \gcd(p,q)=1 gcd(p,q)=1

∴ gcd ⁡ ( p 2 , q ) = 1 \therefore \gcd(p^2,q)=1 gcd(p2,q)=1

∴ d 2 = gcd ⁡ ( p 2 d 2 , q d 2 ) = g c d ( x 2 , z x ) \therefore d^2=\gcd(p^2d^2,qd^2)=gcd(x^2,\frac z x) d2=gcd(p2d2,qd2)=gcd(x2,xz)

∴ d = gcd ⁡ ( x 2 , z x ) \therefore d=\sqrt{\gcd(x^2,\frac zx)} d=gcd(x2,xz)

∴ y = z x d = z x gcd ⁡ ( x 2 , z x ) \therefore y=\frac z{xd}=\frac{z}{x\sqrt{{\gcd(x^2,\frac zx)}}} y=xdz=xgcd(x2,xz) z

code

#include<bits/stdc++.h>
#define fre(x) freopen(#x".in","r",stdin),freopen(#x".out","w",stdout)
#define LL long long
using namespace std;
LL gcd(LL a,LL b){return b?gcd(b,a%b):a;}
int main(){
    int T;LL x,z,Gcd,y;
    scanf("%d",&T);
    while(T--){
        scanf("%lld%lld",&x,&z);
        y=z/x/(LL)(sqrt(gcd(x*x,z/x)));
        if(y*x*gcd(x,y)==z)printf("%lld\n",y);
        else puts("-1");
    }
    return 0;
}
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