hdu1800 Flying to the Mars (字典树)

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题目连接：http://acm.hdu.edu.cn/showproblem.php?pid=1800

题解：the minimum number of broomsticks needed，The soldier who has a higher level could teach the lower , that is to say the former’s level > the latter’s . But the lower can’t teach the higher.说明高level的教低level的,同level不能互教，所以最少 broomsticks ,就是同level最多的soldier。

#include <stdio.h>  #include <string.h>  #define MAXN 3005   int tot;  typedef struct trie  {      int cnt;//当前单词出现的次数        struct trie *child[10];  }trie;    struct trie Trie[MAXN];  struct trie *root;    trie *newtrie()  {//静态分配空间      int i;      trie *ptr;      ptr=&Trie[tot++];      ptr->cnt=0;      for(i=0;i<10;++i)          ptr->child[i]=NULL;      return ptr;  }    int insert(char *str)  {      int i=0,len,index;      trie *ptr=root;      len=strlen(str);      if(len==0)          return 0;  while ((str[i]=='0')&&(i<len-1)){i++;}    for(;i<len;++i)      {          index=str[i]-'0';          if(ptr->child[index]!=NULL)              ptr=ptr->child[index];        else          {ptr->child[index]=newtrie();//新增一节点              ptr=ptr->child[index];//更新节点  }    }  ptr->cnt++;return ptr->cnt;}    int main()  {  int n,ans,temp;    char level[32];while (scanf("%d",&n)!=EOF){ans=tot=0;          root=newtrie(); while (n--){scanf("%s",level);temp=insert(level);if(ans<temp)ans=temp;}printf("%d\n",ans);}    return 0;  }

#include <stdio.h>    #include <string.h>    #define MAXN 3002     int child[MAXN][10];//child[i][j]=0说明没有对应的节点,以i为根节点的子树,    int flag[MAXN],count[MAXN];   int tot,root;      void Trie()    {        memset(child[0],0,sizeof(child[0]));        flag[0]=0;    tot=root=0;//根节点为0    }      int insert(char *str)    {        int *cur=&root,len,i=0;        char *ptr; len=strlen(str);while (str[i]=='0'&&i<len-1){i++;}    for(ptr=str+i;*ptr;++ptr)        {            cur=&child[*cur][*ptr-'0'];            if(*cur==0)            {                *cur=++tot;                    memset(child[tot],0,sizeof(child[tot]));                flag[tot]=0;            }        }        flag[*cur]=1;    return ++count[*cur];    }      int main()  {  int n,ans,temp;    char level[32];while (scanf("%d",&n)!=EOF){memset(count,0,sizeof(count));ans=0;  Trie(); while (n--){scanf("%s",level);temp=insert(level);if(ans<temp)ans=temp;}printf("%d\n",ans);}    return 0;  }