2023-11-29

AtCoder Beginner Contest 042

排序

#include<bits/stdc++.h>
using namespace std;


void solve()
{
	vector<int> a(3);
    for(auto &x : a) cin >> x;
    sort(a.begin,a.end());
    if(a[0] == a[1] && a[1] == 5 && a[2] == 7) cout << "YES\n";
    else cout << "NO\n";
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1;
    while(t--)
        solve();
    return 0;
}

排序

#include<bits/stdc++.h>
using namespace std;


void solve()
{
    vector<string> s(100);
    int n, l;
    cin >> n >> l;
    for(int i = 0; i < n; i++) cin >>s[i];
    
    sort(s.begin(),s.end());
    for(auto x : s) cout << s;
    cout << "\n";
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1;
    while(t--)
        solve();
    return 0;
}

模拟

#include<bits/stdc++.h>
using namespace std;


void solve()
{
    int n, k;
    cin >> n >> k;
    map<int, int> mp;
    for(int i = 0; i < k; i++) 
    {
        int x;
        cin >> x;
        mp[x] = 1;
    }
    
    
    
    for(int i = n; ; i++)
    {
        bool flag = true;
        int j = i;
        while(j)
        {
            int k = j % 10;
            j /= 10;
            if(mp[k]) flag = false;
        }
        
        if(flag) 
        {
            cout << i << "\n";
            return;
        }
    }
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1;
    while(t--)
        solve();
    return 0;
}

组合数学

#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N = 3e5 + 10, mod = 1e9 + 7;
int fac[N], invfac[N];
int qmi(int x, int p = mod - 2)
{
    int res = 1;
    while(p)
    {
        if(p & 1) res = res * (x) % mod;
        x = x * x % mod;
        p >>=1;
    }
    return res;
}
    

void init()
{
	fac[0] = 1;
    for(int i = 1; i < N; i++)
    {
        fac[i] = (fac[i - 1] * i ) % mod;
    }
    invfac[N - 1] = qmi(fac[N - 1]);
    for(int i = N - 2; i >= 0; i--)
    {
        invfac[i] = (invfac[i + 1] * (i + 1)) % mod;
    }
}

int C(int n, int m)
{
    if(n < m || m < 0)
    {
        return 0;
    }
    return fac[n] * invfac[m] % mod * invfac[n - m] % mod;
}

void solve()
{
    init();
    int h, w, a, b;
    cin >> h >> w >> a >> b;
    int ans = 0;
    for(int j = b + 1; j <= w; j++)
    {
        ans += C(h - a + j - 2, j - 1) * C(a + w - j - 1, w - j) % mod;
        ans %= mod;
    }
    cout << ans << "\n";
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1;
    while(t--)
        solve();
    return 0;
}