Atcoder Beginner Contest 273 ABC A~F

Atcoder Beginner Contest 273 ABC

A

题意：

求 A 的阶乘

解法：

暴力

$Code$

# include <bits/stdc++.h>
//# include "windows.h"
# define ll long long
//# define int ll
# define db double
# define mod 998244353
//# define mod 1000000007
# define inf 1000000000
# define INF 1000000000000000000
# define fi first
# define se second
# define pb push_back
# define RI register int
# define vi vector <int>
# define REP(i, n, m) for (RI i = (n);i <= (m);i++)
# define rep(i, n) REP(i, 1, n)
# define foreach(i, c) for (__typeof__((c).end()) i = (c).begin();i != (c).end();i++)
# define pi acos(-1)
# define pii pair <int, int>
using namespace std;
int dx[15] = {
   
   0, 0, 1, -1, -1, -1, 1, 1};
int dy[15] = {
   
   1, -1, 0, 0, -1, 1, -1, 1};

int main(){
   
   
	int n, ans = 1;
	cin >> n;
	for (int i = 1;i <= n;i++) ans *= i;
	cout << ans;
	return 0;
}

B

题意：

给你两个数 $n$ 和 $k$，让你每次求离 $10^i$ 最近的数 $(i\in [1,k])$

解法：暴力

$Code$

# include <bits/stdc++.h>
//# include "windows.h"
# define ll long long
# define int ll
# define db double
# define mod 998244353
//# define mod 1000000007
# define inf 1000000000
# define INF 1000000000000000000
# define fi first
# define se second
# define pb push_back
# define RI register int
# define vi vector <int>
# define REP(i, n, m) for (RI i = (n);i <= (m);i++)
# define rep(i, n) REP(i, 1, n)
# define foreach(i, c) for (__typeof__((c).end()) i = (c).begin();i != (c).end();i++)
# define pi acos(-1)
# define pii pair <int, int>
using namespace std;
int dx[15] = {
   
   0, 0, 1, -1, -1, -1, 1, 1};
int dy[15] = {
   
   1, -1, 0, 0, -1, 1, -1, 1};

signed main(){
   
   
	int n, m, k = 1;
	cin >> n >> m; 
	for (int i = 1;i <= m;i++){
   
   
		k *= 10;
		n = n/k*k + (n%k >= k/2) * k;
	}
	cout << n;
	return 0;
}

C

题意：

你有一个序列 $A=(A_1,A_2,...,A_n$