练习6

practise

A hesorchen

//https://blog.csdn.net/hesorchen
#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <set>
using namespace std;
#define ll long long
#define endl "\n"
#define lowbit(a) (a & (-a))
#define INF 0x3f3f3f3f
#define MAX 1010
#define mod 1000000007
#define PI 3.1415926
int main()
{
    ll a, b;
    cin >> a >> b;
    cout << max(a + b, max(a * b, a - b)) << endl;
    return 0;
}

B hesorchen

//https://blog.csdn.net/hesorchen
#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <set>
using namespace std;
#define ll long long
#define endl "\n"
#define lowbit(a) (a & (-a))
#define INF 0x3f3f3f3f
#define MAX 1010
#define mod 1000000007
#define PI 3.1415926
int main()
{
    string ans = "ABC";
    string temp;
    while (cin >> temp)
    {
        int a = temp[0] - 'A';
        int b = temp[2] - 'A';
        char c;
        c = ans[a];
        ans[a] = ans[b];
        ans[b] = c;
    }
    for (int i = 0; i < 3; i++)
        if (ans[i] == 'A')
        {
            cout << (char)(i + 'A') << endl;
            break;
        }
    return 0;
}

C hesorchen

//https://blog.csdn.net/hesorchen
#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <set>
using namespace std;
#define ll long long
#define endl "\n"
#define lowbit(a) (a & (-a))
#define INF 0x3f3f3f3f
#define MAX 1010
#define mod 1000000007
#define PI 3.1415926
int check(int i)
{
    string temp;
    while (i > 0)
    {
        temp += i % 10 + 'a';
        i /= 10;
    }
    int len = temp.size();
    for (int i = 0; i < len; i++)
    {
        if (temp[i] != temp[len - i - 1])
            return 0;
    }
    return 1;
}
int main()
{
    int n;
    while (cin >> n)
    {
        for (int i = n, j = n;; i++, j--)
        {
            if (check(j))
            {
                cout << j << endl;
                break;
            }
            if (check(i))
            {
                cout << i << endl;
                break;
            }
        }
    }
    return 0;
}

D hesorchen

//https://blog.csdn.net/hesorchen
#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <set>
using namespace std;
#define ll long long
#define endl "\n"
#define lowbit(a) (a & (-a))
#define INF 0x3f3f3f3f
#define MAX 1010
#define mod 1000000007
#define PI 3.1415926
int p[1000100];
int main()
{
    int n;
    cin >> n;
    ;
    int k;
    cin >> k;
    for (int i = 0; i < n; i++)
        cin >> p[i];
    sort(p, p + n);
    cout << p[k - 1] << endl;
    return 0;
}

E hesorchen

//https://blog.csdn.net/hesorchen
#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <set>
using namespace std;
#define ll long long
#define endl "\n"
#define lowbit(a) (a & (-a))
#define INF 0x3f3f3f3f
#define MAX 1010
#define mod 1000000007
#define PI 3.1415926
map<string, int> mp;
int main()
{
    int n;
    cin >> n;
    while (n--)
    {
        string a;
        cin >> a;
        mp[a]++;
    }
    int maxx = 0;
    for (auto it = mp.begin(); it != mp.end(); it++)
        maxx = max(maxx, it->second);
    // cout << maxx << endl;
    for (auto it = mp.begin(); it != mp.end(); it++)
        if (maxx == it->second)
            cout << it->first << endl;
    return 0;
}

F hesorchen

//https://blog.csdn.net/hesorchen
#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <set>
using namespace std;
#define ll long long
#define endl "\n"
#define lowbit(a) (a & (-a))
#define INF 0x3f3f3f3f
#define MAX 1010
#define mod 1000000007
#define PI 3.1415926
int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        string a;
        cin >> a;
        int len = a.size();
        ll s = 0, t = 1;
        for (int i = len - 1; i >= 0; i--)
        {
            if (a[i] == '1')
                s += t;
            t *= 2;
        }
        string ans;
        // cout << s << endl;
        while (s > 0)
        {
            if (s % 3 == 1)
                ans = '1' + ans;
            else if (s % 3 == 2)
                ans = '2' + ans;
            else
                ans = '0' + ans;
            s /= 3;
        }
        cout << ans << endl;
    }
    return 0;
}

G chenyingqi

#include <iostream>
#include <cstdio>
#include <fstream>
#include <algorithm>
#include <cmath>
#include <deque>
#include <vector>
#include <queue>
#include <string>
#include <cstring>
#include <map>
#include <stack>
#include <set>
#include <sstream>
#define IOS ios_base::sync_with_stdio(0); cin.tie(0);
#define ll long long
#define INF 0x3f3f3f3f 
#define MEM(x,y) memset(x,y,sizeof(x))
#define int long long
#define rep(i , a , b) for(int i = a ; i <= b ; i ++)
#define P pair<int,int>
#define  sc(a) scanf("%lld",&a)
#define pf(a) printf("%lld ",a)
using namespace std;
struct point
{
    int x;
    int y;
}point [20];
struct xia
{
    int x;
    int y;
}v[10];
int vis[20];
int maxx;
int n, q;
void ju()
{
    int temp = 0;
    for (int i = 0; i < q; i++)
        for (int j = i+1; j < q; j++)
            if (v[i].x * v[j].y == v[i].y * v[j].x)
                temp++;
    maxx = max(temp, maxx);
    return;
}
void dfs(int x)
{
    while (vis[x])x++;
    if (x >= n) {
        ju();
        return;
    }
    vis[x] = 1;
    for (int i = 0; i < n; i++)
    {
        if (!vis[i])
        {
            vis[i] = 1;
            int dy = point[x].y - point[i].y;
            int dx = point[x].x - point[i].x;
            v[q].x = dx, v[q].y = dy;
            q++;
            dfs(x + 1);
            q--;
            vis[i] = 0;
        }
    }
    vis[x] = 0;
    return;
}
signed main()
{
    sc(n);
    MEM(vis, 0);
    rep(i, 0, n - 1)
        sc(point[i].x), sc(point[i].y);
    dfs(0);
    cout << maxx << endl;
}

H puluo

#include<stdio.h>
const long long mod=1e9+7;
long long pre[200005];
/*快速幂板子*/
long long qmul(long long a,long long b)
{
    long long res=1;
    while(b)
    {
        if(b&1)res=res*a%mod;
        a=a*a%mod;
        b>>=1;
    }
    return res%mod;
}
/*组合数板子*/
long long C(int a,int b)
{
    long long res=1,i,j;
    for(i=1,j=a;i<=b;i++,j--)
    {
        res=res*j%mod;
        res=res*qmul(i,mod-2)%mod;
    }
    return res;
}
int main()
{
    long long n,a,b,ans;
    pre[0]=1;
    for(int i=1;i<=200005;i++)pre[i]=pre[i-1]*i%mod;
    scanf("%lld%lld%lld",&n,&a,&b);
    ans=(qmul(2,n)-1)-C(n,a)-C(n,b);
    while(ans<0)ans+=mod;
    printf("%lld\n",ans);
}

I lnkkerst

#include <iostream>
#include <cstring>
using namespace std;
int n, m, e[51][51], ans, u[51 << 1], v[51 << 1];
bool vis[51];
void dfs(int node) {
    vis[node] = 1;
    for(int i = 1; i <= n; ++i) {
        if(i == node) continue;
        if(!vis[i] && e[node][i]) dfs(i);
    }
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(NULL);
    cin >> n >> m;
    for(int i = 1; i <= m; ++i) {
        cin >> u[i] >> v[i];
        e[u[i]][v[i]] = e[v[i]][u[i]] = 1;
    }
    for(int i = 1; i <= m; ++i) {
        e[u[i]][v[i]] = e[v[i]][u[i]] = 0;
        memset(vis, 0, sizeof(vis));
        dfs(1);
        for(int i = 1; i <= n; ++i)
            if(!vis[i]) {
                ++ans;
                break;
            }
        e[u[i]][v[i]] = e[v[i]][u[i]] = 1;
    }
    cout << ans;
    return 0;
}