Codeforces Round #651 (Div. 2)

syx这场比赛打zbl，严重降智，觉得开始写cf题解

CF1370A Maximum GCD

#include<bits/stdc++.h>
using namespace std;
#define int long long
namespace Fread {
	const int MAXN=1<<20;
	char buf[MAXN],*S,*T;
	inline char getchar() {
		if (S==T) {
			T=(S=buf)+fread(buf,1,MAXN,stdin);
			if (S==T) return EOF;
		}
		return *S++;
	}
}
inline int read() {
	int x(0),neg(1);
	char ch=getchar();
	while(!isdigit(ch)) {
		if (ch=='-') neg=-1;
		ch=getchar();
	}
	while(isdigit(ch)) {
		x=(x<<1)+(x<<3)+(ch-'0');
		ch=getchar();
	}
	return x*neg;
}
#ifdef ONLINE_JUDGE
	#define getchar Fread::getchar
#endif
int n;
signed main() {
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	int T=read();
	while(T--) {
		n=read();
		if (n%2==0) {
			printf("%lld\n",n/2);
		}
		else {
			printf("%lld\n",(n-1)/2);
		}
	}
	return 0;
}

CF1370B GCD Compression

显然可以贪
假设gcd为2，那么你只需要把奇数分一类，偶数分一类，取奇数和奇数一组，偶数和偶数一组