UVA 494 Kindergarten Counting Game map

Everybody sit down in a circle. Ok. Listen to me carefully.
“Woooooo, you scwewy wabbit!”
Now, could someone tell me how many words I just said?
Input
Input to your program will consist of a series of lines, each line containing multiple words (at least one).
A “word” is defined as a consecutive sequence of letters (upper and/or lower case).
Output
Your program should output a word count for each line of input. Each word count should be printed
on a separate line.
Sample Input
Meep Meep!
I tot I taw a putty tat.
I did! I did! I did taw a putty tat.
Shsssssssssh ... I am hunting wabbits. Heh Heh Heh Heh ...
Sample Output
2
7
10
9

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<string>
#include<map>
using namespace std;
#define maxn 1010
int main()
{
    char c;
    int j;
    char str[maxn];
    int num = 0;
    map<string,int>mm;
    while(~(c = getchar()))
    {
        if(num == 0)
        {
            memset(str,0,sizeof(str));
            mm.clear();
            j = 0;
        }
        if(!isalpha(c)&&c!='\n')//注意只要不是空格都可以将一串字符隔开成几个单词
        {
            str[j] = '\0';
            mm[str]++;
            memset(str,0,sizeof(str));
            j = 0;
        }
        else if(c == '\n')
        {
            num = 0;
            str[j] = '\0';
            mm[str]++;
            int count = 0;
            for(map<string,int>::iterator it = mm.begin();it!=mm.end();it++)
            {
                //cout << it -> first << endl;
                if(isalpha(it->first[0]))
                {
                    //cout << it -> first[0] << endl;
                    count += it -> second;
                }
                //cout << count << endl;
            }
            cout << count << endl;
            continue;
        }
        else str[j++] = c;
        num++;
    }
    return 0;
}