codeforce 1091

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题目连接：http://codeforces.com/contest/1091

A：

#include <bits/stdc++.h>
using namespace std;
int main() {
	int y, b, r;
	cin >> y >> b >> r;
	cout << min(y, min(b - 1, r - 2)) * 3 + 3 << endl;
	return 0;
}

B：

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main() {
	ll n, x = 0, y = 0, a = 0, b = 0;
	cin >> n;
	for (int i = 0; i < n * 2; i++) {
		cin >> x >> y;
		a += x;
		b += y;
	}
	cout << a / n << ' ' << b / n << endl;
	return 0;
}

C:

答案个数就是因子个数，然后计算以这个因子递增的所有数字。

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 9;
int main() {
	int n;
	cin >> n;
	vector<long long> p;
	for (int i = 1; i * i <= n; i++) {
		if (n % i == 0) {
			p.push_back(i);
			if (i * i != n)
			p.push_back(n / i);
		}
	}
	sort(p.begin(), p.end());
	for (int i = p.size() - 1; i >= 0; i--) {
		long long x = n / p[i], y = p[i];
		cout << (x - 1) * x / 2 * y + x;
		if (i == 0) {
			cout << endl;
		} else {
			cout << ' ';
		}
	}
	return 0;
}

D:

找规律

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e6 + 9;
const int mod = 998244353;
ll f[N];
int main() {
	ll n;
	while (cin >> n) {
		f[1] = 1;
		f[2] = 2;
		ll tmp = 2;
		for (ll i = 3; i <= n; i++) {
			f[i] = (f[i - 1] + tmp - 1) % mod * i % mod;
			tmp = tmp * i % mod;
		}
		cout << f[n] << endl;
	}
	return 0;
}

E

F

G