小比赛

密码：123456

1001 http://acm.hdu.edu.cn/diy/contest_showproblem.php?pid=1001&cid=16288&hide=0

模拟题目，不过在pos赋初值的时候弄错了，我的pos要的到的值是0-n-1而我给赋值成0了，因为我要用它来判断。所以纠结了老久了才检查到。

这种错误很难找的。提醒一下自己认真！

#include <cstdio>
#include <cstring>
#include <iostream>
#define maxn 5007
using namespace std;

int a[maxn],b[maxn];
int n,m;

int main()
{
    int ti,i;
    int x,y;
    char op[2];
    scanf("%d",&ti);
    while (ti--)
    {
        scanf("%d%d",&n,&m);
        n /= 2;
        for (i = 0; i < n; ++i) a[i] = i;
        for (i = n ; i < 2*n; ++i) b[i - n] = i;
        while (m--)
        {
            scanf("%s%d",op,&x);
            x--;
            if (op[0] == 'Q')
            {
                int pos = 0;
                for (i = 0; i < n; ++i)
                {
                    if (a[i] == x)
                    {
                        pos = i; break;
                    }
                }
                if (i < n)
                printf("%d %d %d\n",a[(pos - 1 + n)%n] + 1,a[(pos + 1)%n] + 1,b[pos] + 1);
                else
                {
                    for (i = 0; i < n; ++i)
                    {
                        if (b[i] == x)
                        {
                            pos = i; break;
                        }
                    }
                    printf("%d %d %d\n",b[(pos - 1 + n)%n] + 1,b[(pos + 1)%n] + 1,a[pos] + 1);
                }
            }
            else
            {
                scanf("%d",&y); y--;
                if (op[0] == 'A')
                {
                    int pos1 = 0,pos2 = 0;
                    for (i = 0; i < n; ++i)
                    {
                        if (a[i] == x)
                        {
                            pos1 = i; break;
                        }
                    }
                    if (i < n)
                    {
                        for (i = 0; i < n; ++i)
                        {
                            if (b[i] == y)
                            {
                                pos2 = i; break;
                            }
                        }
                    }
                    else
                    {
                        for (i = 0; i < n; ++i)
                        {
                            if (a[i] == y)
                            {
                                pos1 = i; break;
                            }
                        }
                        for (i = 0; i < n; ++i)
                        {
                            if (b[i] == x)
                            {
                                pos2 = i; break;
                            }
                        }
                    }
                     int t = a[pos1];
                     a[pos1] = b[pos2];
                     b[pos2] = t;
                }
                else if (op[0] == 'B')
                {
                    int pos1 = -1,pos2 = -1;
                    for (i = 0; i < n; ++i)
                    {
                        if (a[i] == x) pos1 = i;
                        if (a[i] == y) pos2 = i;
                        if (pos1 > -1&&pos2 > -1) break;
                    }
                    if (i < n)
                    {
                        int t = a[pos1];
                        a[pos1] = a[pos2];
                        a[pos2] = t;
                    }
                    else
                    {
                        int pos1 = -1,pos2 = -1;//就是这里赋初值的时候弄错了
                        for (i = 0; i < n; ++i)
                        {
                            if (b[i] == x) pos1 = i;
                            if (b[i] == y) pos2 = i;
                            if (pos1 > -1&&pos2 > -1) break;//因为这里要判断的
                        }
                        int t = b[pos1];
                        b[pos1] = b[pos2];
                        b[pos2] = t;
                    }
                }
            }
        }
    }
    return 0;
}

1002笛卡尔树，还没研究。http://acm.hdu.edu.cn/diy/contest_showproblem.php?pid=1002&cid=16288&hide=0

1003：http://acm.hdu.edu.cn/diy/contest_showproblem.php?pid=1003&cid=16288&hide=0

暴力做的，才开始我是记录的所有前两个字符串s1 s2搜索到的四进制形式，然后与四进制s3比较，这样相当麻烦，写了一晚上没A.后来改成十进制，求和后然后在转化成4进制与四进制s3比较，可是还是WA最后虎哥提醒了一组数据？？？12 与 312如果最后还是四进制比较的话很麻烦不好写。转化思路，本来我以为3个dfs记录所有搜到的十进数，要O(n^3)可是虎哥提醒第三组数据hash[]就行，才恍然大悟，只需O(n^2)即可，hash[i]来表示i是否存在。

#include <cstdio>
#include <cstring>
#include <iostream>
#define maxn 4097
#define N 10
using namespace std;

int res1[maxn],res2[maxn],res3[maxn*2];
int r1,r2;
char s1[N],s2[N],s3[N];
int len1,len2,len3;

void dfs1(int num)
{
    if (num == len1 - 1)
    {
        for (int k = 0; k < len1; ++k)
        {
            res1[r1] = res1[r1]*4 + s1[k] - '0';
        }
        r1++;
        return ;
    }
    if (s1[num + 1] != '?') dfs1(num + 1);
    else
    {
        for (int i = 0; i <= 3; ++i)
        {
            s1[num + 1] = i + '0';
            dfs1(num + 1);
            s1[num + 1] = '?';
        }
    }
}

void dfs2(int num)
{
    if (num == len2 - 1)
    {
        for (int k = 0; k < len2; ++k)
        {
            res2[r2] = res2[r2]*4 + s2[k] - '0';
        }
        r2++;
        return ;
    }
    if (s2[num + 1] != '?') dfs2(num + 1);
    else
    {
        for (int i = 0; i <= 3; ++i)
        {
            s2[num + 1] = i + '0';
            dfs2(num + 1);
            s2[num + 1] = '?';
        }
    }
}

void dfs3(int num)
{
    if (num == len3 - 1)
    {
        int sum = 0;
        for (int k = 0; k < len3; ++k)
        {
            sum = sum*4 + s3[k] - '0';
        }
        res3[sum] = 1;
        return ;
    }
    if (s3[num + 1] != '?') dfs3(num + 1);
    else
    {
        for (int i = 0; i <= 3; ++i)
        {
            s3[num + 1] = i + '0';
            dfs3(num + 1);
            s3[num + 1] = '?';
        }
    }
}

int main()
{
    int i,j;
   // printf("%c",1 + '0');
    while (~scanf("%s",s1))
    {
         r1 = r2 = 0;
         scanf("%s",s2);
         scanf("%s",s3);
         len1 = strlen(s1);
         len2 = strlen(s2);
         len3 = strlen(s3);
         memset(res1,0,sizeof(res1));
         memset(res2,0,sizeof(res2));
         memset(res3,0,sizeof(res3));
        //搜做第一个字符串的所有可能
        if (s1[0] != '?') dfs1(0);
        else
        {
            for (j = 0; j <= 3; ++j)
            {
                s1[0] = j + '0';
                dfs1(0);
                s1[0] = '?';
            }
        }
       /* printf("%d\n",r1);
        for (i = 0; i < r1; ++i) printf("%d\n",res1[i]);
        printf("****************************\n");*/
        //搜做第二个字符串的所有可能
        if (s2[0] != '?') dfs2(0);
        else
        {
            for (j = 0; j <= 3; ++j)
            {
                s2[0] = j + '0';
                dfs2(0);
                s2[0] = '?';
            }
        }
        /*printf("%d\n",r2);
        for (i = 0; i < r2; ++i) printf("%d\n",res2[i]);
        printf("****************************\n");*/

        //搜做第二个字符串的所有可能
        if (s3[0] != '?') dfs3(0);
        else
        {
            for (j = 0; j <= 3; ++j)
            {
                s3[0] = j + '0';
                dfs3(0);
                s3[0] = '?';
            }
        }
        //检验
        int ct = 0;
        for (i = 0; i < r1; ++i)
        {
            for (j = 0; j < r2; ++j)
            {
                int tmp = res1[i] + res2[j];
                 if (res3[tmp]) ct++;
            }
        }
        printf("%d\n",ct);
    }
    return 0;
}

1004 http://acm.hdu.edu.cn/diy/contest_showproblem.php?pid=1004&cid=16253&hide=0

就是裸的求反素数：

#include <cstdio>
#include <cstring>
#define ll long long
using namespace std;

const int inf = 999999999;
const int prime[16]= {1,2,3,5,7,11,13,17,19,23,29,31,37,41,43,47};
int n;
ll bnum,bsum;

void getantiprime(ll num,ll k,ll sum,ll limit)
{
    if (bsum < sum)
    {
        bsum = sum;
        bnum = num;
    }
    if (bsum == sum && bnum > num) bnum = num;
    if (k > 10) return ;
    ll tmp = num;
    for (int i = 1; i <= limit; ++i)
    {
        if (tmp*prime[k] > n) break;
        tmp = tmp*prime[k];
        getantiprime(tmp,k + 1,sum*(i + 1),i);
    }
}
int main()
{
    int t;
    scanf("%d",&t);
    while (t--)
    {
        bsum = -inf; bnum = inf;
        scanf("%d",&n);
        getantiprime(1,1,1,50);
        printf("%lld\n",bnum);
    }
    return 0;
}

1005http://acm.hdu.edu.cn/diy/contest_showproblem.php?pid=1005&cid=16288&hide=0

字典树做法：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#define maxn 50007
using namespace std;


struct node
{
    int flag;
    node *next[27];
}*head,H[100000];
int n,m,pos;
char str[maxn][23];

node* newnode()
{
    node *q = &H[pos++];
    for (int i = 0; i< 26; ++i)
    q->next[i] = NULL;
    q->flag = 0;
    return q;
}
void insert(char *s)
{
    int i,k;
    int len = strlen(s);
    node *p = head;
    for (i = 0; i < len; ++i)
    {
        k = s[i] - 'a';
        if (p->next[k] == NULL)
        p->next[k] = newnode();
        p = p->next[k];
    }
    p->flag = 1;
}
bool search(char *s)
{
    int i,k;
    int len = strlen(s);
    node *p = head;
    for (i = 0; i < len; ++i)
    {
        k = s[i] - 'a';
        if (p->next[k]) p = p->next[k];
        else
        return false;
    }
    if (p->flag) return true;
    else return false;
}

int main()
{
    int i;
    while (~scanf("%d%d",&n,&m))
    {
        memset(H,0,sizeof(H));
        pos = 0;
        head = &H[pos++];
        for (i = 0; i < n; ++i)
        {
            cin>>str[i];
        }
       // for (i = 0; i< n; ++i) printf("%s\n",str[i]);
        char tmp[23];
        for (i = 0; i < m; ++i)
        {
            scanf("%s",tmp);
            insert(tmp);
        }
        int ct = 0;
        for (i = 0; i < n; ++i)
        {
            if (!search(str[i]))
            {
                insert(str[i]);
                ct++;
            }
        }
        printf("%d\n",ct);
    }
    return 0;
}

set做法：

#include <iostream>
#include <string>
#include <cstdio>
#include <map>
#include <set>
#define maxn 50010
using namespace std;

set<string>S;
string str[maxn];

int main()
{
   int n,m;
   while (~scanf("%d%d",&n,&m))
   {
       S.clear();
       for (int i = 0; i < n; ++i)
       cin>>str[i];

       string s;
       int ct = 0;
       for (int i = 0; i < m; ++i)
       {
           cin>>s;
           S.insert(s);
       }

       for (int i = 0; i < n; ++i)
       {
           if (S.find(str[i]) == S.end())
           {
               S.insert(str[i]);
               ct++;
           }
       }
       printf("%d\n",ct);
   }
   return 0;
}

map做法：

#include <iostream>
#include <string>
#include <cstdio>
#include <map>
#include <set>
#define maxn 50010
using namespace std;

map <string,int> mp;
string str[maxn];

int main()
{
   int n,m;
   while (~scanf("%d%d",&n,&m))
   {
       mp.clear();
       for (int i = 0; i < n; ++i)
       cin>>str[i];

       string s;
       int ct = 0;
       for (int i = 0; i < m; ++i)
       {
           cin>>s;
           mp[s] = 1;
       }

       for (int i = 0; i < n; ++i)
       {
           if (!mp[str[i]])
           {
               ct++;
               mp[str[i]] = 1;
           }
       }
       printf("%d\n",ct);
   }
   return 0;
}