poj 2418 Hardwood Species

http://poj.org/problem?id=2418

题意：给定一些树，按字典序输出数名和树出现的频率；

思路：这个题用二叉搜索树可以做，同时在网上看到了一个简单的方法，用map来做，这里map真是太好用了；

map做法：

#include <iostream>
#include <map>
#include <cstdio>
#include <string>
using namespace std;
int main()
{
    string a;
    map<string,int>tree;
    double n = 0;
    char ss[35] = {NULL};
    while(gets(ss))
    {
        a = ss;
        ++tree[a];
        ++n;
    }
    map<string,int>::iterator temp;
    for(temp = tree.begin(); temp != tree.end(); ++temp)
    {
        cout<<temp->first<<" ";
        printf("%.4f\n",(temp->second)*100.0/n);
    }
    return 0;
}

二叉搜索树：

刚开始用stirng存名字，G++就是tle而c++就是CE ,无语了；

代码：

#include <iostream>
#include <cstring>
#include <algorithm>
#include <cstdio>
using namespace std;
struct node
{
   char s[40];
    int n;
    node *left,*right;
};
int n = 0;
node *get()
{
    node *tt = NULL;
    tt = new node;
    tt->n = 1;
    tt->left = NULL;
    tt->right = NULL;
    return tt;
}
node *head = NULL;
node *temp = NULL;
char str[40] = {NULL};
void insert(char *str,node *t)
{
    if(strcmp(str,t->s) == 0)
    ++t->n;
    else
    if(strcmp(str,t->s) < 0)
    {
        if(t->left == NULL)
        {
            t->left = get();
            t->left->n = 1;
            strcpy(t->left->s,str);
            return ;
        }
        else
        insert(str,t->left);
    }
    else
    {
        if(t->right == NULL)
        {
            t->right = get();
            t->right->n = 1;
          strcpy(t->right->s,str);
          return ;
        }
        else
        insert(str,t->right);
    }
}
void output(node *tt)
{
    if(tt->left == NULL && tt->right == NULL)
   {
       printf("%s %.4f\n",tt->s,tt->n*100.00/n);
       return ;
   }
    if(tt->left)
    output(tt->left);
       printf("%s %.4f\n",tt->s,tt->n*100.00/n);
       if(tt->right)
    output(tt->right);
}
int main()
{
    //freopen("input.txt","r",stdin);
    gets(str);
    head = get();
    strcpy(head->s,str);
    head->n = 1;
    //puts(head->s);
    n = 1;
   while(gets(str) != NULL)
   {
       ++n;
       insert(str,head);
   }
   //printf("%d\n",n);
   output(head);
   return 0;
}