第六次寒假训练赛题解

A CodeForces - 21A

简单模拟，模就完事了

#include<bits/stdc++.h>
using namespace std;
bool judge(int c)
{
    return (c>=97&&c<=122)||(c>=65&&c<=90)||(c>=48&&c<=57)||c==95;
}
int main()
{
    int t=0;
    int c=getchar();
    while(judge(c))
    {
        t++;
        c=getchar();
    }
    if(t>=1&&t<=16&&c=='@')
    {
L:
        t=0;
        c=getchar();
        while(judge(c))
        {
            t++;
            c=getchar();
        }
        if(t>=1&&t<=16)
        {
            if(c=='\n')
                cout << "YES" << endl;
            else if(c=='.')
                goto L;
            else if(c=='/')
            {
                t=0;
                c=getchar();
                while(judge(c))
                {
                    t++;
                    c=getchar();
                }
                if(t>=1&&t<=16&&c=='\n')
                    cout << "YES" << endl;
                else cout << "NO" << endl;
            }else cout << "NO" << endl;
        }else cout << "NO" << endl;
    } else cout << "NO" << endl;
    return 0;
}

B CodeForces - 49B

简单模拟，模就完事了

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int a,b;
    cin >> a >> b;
    int t=a,d=2;
    while(t)
    {
        d=max(d,t%10+1);
        t/=10;
    }
    t=b;
    while(t)
    {
        d=max(d,t%10+1);
        t/=10;
    }
    t=0;
    int k=1;
    while(a||b)
    {
        t+=(a%10)*k;
        t+=(b%10)*k;
        a/=10;
        b/=10;
        k*=d;
    }
    int ans=0;
    while(t)
    {
        t/=d;
        ans++;
    }
    cout << ans << endl;
    return 0;
}

C CodeForces - 128B

优先队列，后缀自动机也可，这里只写优先队列的方法

#include <bits/stdc++.h>
using namespace std;
struct str
{
    string s;
    int num;
    bool operator <(const str &x)const
    {
        if(x.s==s)
            return num>x.num;
        return s>x.s;
    }
} x;
int main()
{
    priority_queue<str> q;
    string s;
    int n;
    cin>>s;
    cin>>n;
    for(int i=0; i<s.size(); i++)
    {
        x.s=s[i];
        x.num=i;
        q.push(x);
    }
    while(!q.empty())
    {
        x=q.top();
        q.pop();
        n--;
        if(!n)
            break;
        if(x.num<s.size()-1)
        {
            x.num++;
            x.s+=s[x.num];
            q.push(x);
        }
    }
    if(n)
        cout<<"No such line."<<endl;
    else
        cout<<x.s<<endl;
return 0;
}

D CodeForces - 190C

简单递归一下就行

#include <bits/stdc++.h>
using namespace std;
string s,ans;
bool flag= true;
void input()
{
    if (cin >> s)
    {
        ans+=s;
        if (s=="pair")
        {
            ans+='<';
            input();
            ans+=',';
            input();
            ans+='>';
        }
    }
    else
        flag= false;
}

int main()
{
    cin >> s;
    input();
    if (cin >> s)
        flag= false;
    if(flag)
        cout << ans << endl;
    else
        cout << "Error occurred" << endl;
    return 0;
}

E CodeForces - 798B

暴力算最值

#include<bits/stdc++.h>
using namespace std;
int n;
string a[55],t;
int sum=1<<30;
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)
        cin>>a[i];
    for(int i=0;i<n;i++)
    {
        int ans=0;
        for(int j=0;j<n;j++)
        {
            if(i==j) continue;
            t=a[j]+a[j];
            if(t.find(a[i])==-1)
            {
                cout<<-1<<endl;
                return 0;
            }
            ans+=t.find(a[i]);
        }
        sum=min(ans,sum);
    }
    cout << sum << endl;
    return 0;
}

F CodeForces - 1043C

字典序最小的时候s必然是前面全是a，后面全是b这个样子，以此为规则模拟一下会发现只要是s[i]!=s[i+1]就应该翻转

#include <bits/stdc++.h>
using namespace std;
string s,ans="";
int main()
{
    cin >> s;
    for(int i=0;i<s.size()-1;i++)
    {
        if(s[i]!=s[i+1])ans+="1 ";
        else ans+="0 ";
    }
    if(s[s.size()-1]=='a')ans+="1";
    else ans+="0";
    cout << ans << endl;
    return 0;
}