传送门：Dashboard - Codeforces Round 992 (Div. 2) - Codeforces

A. Game of Division

思路：模拟

AC代码：Submission #295676347 - Codeforces

B. Paint a Strip

思路：数学 + 贪心

放置的位置一定是 1  4  10  22  48  .....

放置的位置 一定是 2 * i + 2

AC代码：Submission #295676364 - Codeforces

C. Ordered Permutations

题意：

思路：

打表找规律

打表代码：

#include<bits/stdc++.h>
using namespace std;
int n, ans;
vector<vector<int>> res;
int a[55];
int used[55];
void dfs(int d) {
	if (d > n) {
		int h = 0;
		for (int i = 1; i <= n; i++) {
			for (int j = i; j <= n; j++) {
				int k = 1e9;
				for (int t = i; t <= j; t++) {
					k = min(a[t], k);
				}
				h += k;
			}
		}
		if (h > ans) {
			ans = h;
			res.clear();
		}
		if (h == ans) {
			vector<int> temp(n + 1);
			for (int i = 1; i <= n; i++) temp[i] = a[i];
			res.push_back(temp);
		}
		return;
	}
	for (int i = 1; i <= n; i++) {
		if (!used[i]) {
			a[d] = i;
			used[i] = 1;
			dfs(d + 1);
			used[i] = 0;
		}
	}
}
int main() {
	for (int i = 1; i <= 10; i++)
	{
		res.clear();
		n = i;
		dfs(1);
		cout << i << " " << res.size() << endl;
		for (auto e : res)
		{
			for (int j = 1; j < e.size(); j++) cout << e[j] << " ";
			cout << endl;
		}
		cout << endl;
	}
	return 0;
}

eg : n == 5

1 在最左边的出现的次数是 8 ，2 的最左边的出现的次数 4

数字 i 出现的次数是 1 << ( n - i - 1 ) 

模拟

AC代码：

#include<bits/stdc++.h>
using namespace std;
#define int long long
void solve()
{
    int n , k; 
    cin >> n >> k;
    // 2 的 60 次方 > 1e12 
    if( n <= 61 && 1ll << ( n - 1 ) < k ){
        puts("-1"); return;
    }
    k--;
    vector<int> a(n);
    int l = 0 , r = n;
    for( int i = 1 ; i < n ; i++ )
    {
        if( n - i - 1 >= 60 || 1ll << ( n - i - 1 ) > k ){
            a[l++] = i; // 放在最左边
        }
        else{
            k -= 1ll << ( n - i - 1 );
            a[--r] = i; // 放在最右边
        }
    }
    a[l] = n;
    for( int i = 0 ; i < n ; i++ ) cout << a[i] << " ";
    cout << endl;
}
signed main()
{
    int tt ; cin >> tt;
    while(tt--)solve();
    return 0;
}