GCD (Greatest Common Divisor)

欧几里德算法（GCD），又称辗转相除法。

//代码一：int gcd(int a, int b){     return b ? gcd(b, a%b):a;}

//代码二：int gcd(int a, int b){while((a %= b) && (b %= a)) ;return a + b;}

练习题：1、Uva 10193  All you need is love //P.S.The Beatles的歌名《All You Need Is Love》。

//扯了一大堆，原来就是求两个数是否互质。。

#include <iostream>#include <cstring>using namespace std;int gcd(int a,int b){return b? gcd(b, a%b):a;}int main(){int a, b;int T;char s[32];int i, n;cin>>T;n=1;while(n<=T){cout<<"Pair #"<<n++<<": ";cin>>s;a = 0;for(i=0;s[i];++i){a =a*2+s[i]-'0';}cin>>s;b = 0;for(i=0;s[i];++i){b =b*2+s[i]-'0';}if(gcd(a,b)==1) cout<<"Love is not all you need!\n";elsecout<<"All you need is love!\n";}return 0;}