第三届“传智杯”全国大学生IT技能大赛（初赛B组）

#include 
using namespace std;
int n, v, m, a;
int main()
{
	cin >> n >> v >> m >> a;
	int sum = 0;
	for (int i = 0; i < n; i++)
	{
		if (i % m == 0&&i)v += a;
		sum += v;
	}
	cout << sum << endl;
}

#include 
using namespace std;
int main()
{
	int x;
	cin >> x;
	if (x >= 90)printf("4.0n");
	else if (x >= 60 && x <= 89)
		printf("%.1fn", 4 - (90 - x) * 0.1);
	else
	{
		if (sqrt(x) * 10 < 60)printf("0.0n");
		else printf("%.1fn", 4 - (90 - (int)(sqrt(x) * 10)) * 0.1);
	}
	return 0;
}

#include 
using namespace std;
const int N = 500010;
struct node
{
	int id;
	int k;
	int w;
	int score;
}a[N];
int n;
bool cmp(node a, node b)
{
	if(a.score!=b.score)
	return a.score > b.score;
	else
	{
		if (a.w != b.w)return a.w > b.w;
		else return a.id < b.id;
	}
}
int main()
{
	cin >> n;
	int k, w;
	for (int i = 1; i <= n; i++)
	{
		cin >> a[i].w >> a[i].k;
		a[i].score = a[i].w * a[i].k;
		a[i].id = i;
	}
	sort(a + 1, a + n + 1, cmp);
	for (int i = 1; i <= n; i++)
		cout << a[i].id << ' ';
	return 0;
	
}

#include 
using namespace std;
const int N = 1010;
int n;
int idx;
int cnt;
string fil[N];
int main()
{
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		string op;
		string a, b;
		cin >> op;
		if (op == "touch")
		{
			cin >> a;
			bool f = false;
			for (int j = 0; j < idx; j++)
				if (fil[j] == a)
				{
					f = true;
					break;
				}
			if (!f)fil[idx++] = a;
		}
		if (op == "rm")
		{
			cin >> a;
			for (int j = 0; j < idx; j++)
				if (fil[j] == a)cnt = j;
			for (int j = cnt; j < idx; j++)
				fil[j] = fil[j + 1];
			idx--;
		}
		if (op == "ls")
		{
			for (int j = 0; j < idx; j++)
				cout << fil[j] << endl;
		}
		if (op == "rename")
		{
			cin >> a;
			string b;
			cin >> b;
			for (int j = 0; j < idx; j++)
			{
				if (fil[j] == a)
				{
					fil[j] = b;
					break;
				}
			}
		}
	}
	return 0;
}

#include 
using namespace std;
typedef long long LL;
const int MOD = 1e9 + 7;
int n, m;
int t_count;
void dfs(int u,LL number)
{
	if (u > n)
	{
		if (number % m == 0)t_count++;
		return;
	}
	for (int i = 1; i <= 6; i++)
	{
		dfs(u + 1, number * 10 + i);
	}
}
int main()
{
	cin >> n >> m;
	dfs(1, 0);
	cout << t_count << endl;
}