4968. 互质数的个数 - AcWing题库

涉及：快速幂，欧拉函数，分解质因数

 

#include <bits/stdc++.h>		

#define fi first
#define se second
#define endl '\n'
#define pb push_back

using namespace std;
using LL = long long;


const int mod = 998244353;

const int N = 1e5 + 10; 

LL a,b;

LL mo(LL n)
{
	return (n % mod + mod) % mod;
}

LL qmi(LL a,LL b)
{
	LL res = 1;
	while(b)
	{
		if (b & 1) res = res * a % mod;
		a = a * a % mod,b >>= 1;
	}
	return res;
}

LL eular(LL n)
{
	LL res = n;
	for (int i = 2;i <= n / i;i ++)
	{
		if (n % i) continue;
		res = res / i * (i - 1);
		while(n % i == 0) n /= i;
	}
	if (n > 1) res = res / n * (n - 1);
	return res;
}

void solve()
{
	cin >> a >> b;
	if (a == 1) cout << 0 << endl;
	else    cout << mo(eular(a) * qmi(a,b - 1)) << endl;
}

int main()
{
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int _ = 1;
	// cin >> _;
	while(_--) solve();
	
	return 0;
}	

5395. 平均 - AcWing题库 简单

贪心

#include <bits/stdc++.h>		

#define fi first
#define se second
#define endl '\n'
#define pb push_back

using namespace std;
using LL = long long;
typedef pair<int,int> PII;
const LL inf = 0x3f3f3f3f3f3f3f3f;
const int INF = 0x3f3f3f3f;

const int mod = 998244353;


const int N = 1e5 + 10; 

vector<LL> v[12];

int n;

bool cmp(const LL &a,const LL &b)
{
	return a > b;
}

void solve()
{
	cin >> n;
	for (int i = 1;i <= n;i ++)
	{
		LL a,b; cin >> a >> b;
		v[a].push_back(b);
	}
	
	for (int i = 0;i < 10;i ++) sort(v[i].begin(),v[i].end(),cmp);
	
	LL ans = 0;
	LL cnt = n / 10;
	for (int i = 0;i < 10;i ++)
	{
		if (v[i].size() > cnt) 
			for (int j = cnt;j < v[i].size();j ++) 
				{
					ans += v[i][j];
					// cout << v[i][j] << "==" << endl;
				}
	}
	
	cout << ans << endl;
}


int main()
{
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int _ = 1;
	// cin >> _;
	while(_--) solve();
	
	return 0;
}	

4965. 三国游戏 - AcWing题库

贪心

 

 

#include <bits/stdc++.h>		

#define fi first
#define se second
#define endl '\n'
#define pb push_back

using namespace std;
using LL = long long;
typedef pair<int,int> PII;
const LL inf = 0x3f3f3f3f3f3f3f3f;
const int INF = 0x3f3f3f3f;

const int mod = 998244353;


const int N = 1e5 + 10; 

LL a[N],b[N],c[N],w[N];
int n;


LL work(LL a[],LL b[],LL c[])//a是获胜国,其他是失败国
{
	LL res = -1;
	LL sum = 0;
	for (int i = 1;i <= n;i ++) w[i] = a[i] - b[i] - c[i];
	
	sort(w + 1,w + 1 + n,greater<LL>());//从大到小排序
	
	for (int i = 1;i <= n;i ++)
	{
		sum += w[i];
		if (sum > 0) res = i;
		else break; 
	}
	
	return res;
	
}


void solve()
{
	cin >> n;
	for (int i = 1;i <= n;i ++) cin >> a[i];
	for (int i = 1;i <= n;i ++) cin >> b[i];
	for (int i = 1;i <= n;i ++) cin >> c[i];
	
	cout << max({work(a,b,c),work(b,a,c),work(c,a,b)}) << endl;
}


int main()
{
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int _ = 1;
	// cin >> _;
	while(_--) solve();
	
	return 0;
}