题意:在\(1\)~\(n\)中找两个不相等的数使得他们的\(gcd\)最大.

题解:水题,如果\(n\)是偶数,那么一定取\(n\)和\(n/2\),\(n\)是奇数的话,取\(n-1\)和\((n-1)/2\).

代码:

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
#include <map>
#include <set>
#include <unordered_set>
#include <unordered_map>
#define ll long long
#define fi first
#define se second
#define pb push_back
#define me memset
const int N = 1e6 + 10;
const int mod = 1e9 + 7;
const int INF = 0x3f3f3f3f;
using namespace std;
typedef pair<int,int> PII;
typedef pair<ll,ll> PLL;

int t;
int n;

int main() {
    ios::sync_with_stdio(false);cin.tie(0);
	cin>>t;
	 while(t--){
	 	cin>>n;
	 	if(n%2==0){
	 		cout<<n/2<<endl;
	 	}
	 	else{
	 		cout<<(n-1)/2<<endl;
	 	}
	 }

    return 0;
}