uva 10815 Andy's First Dictionary（快排、字符串）

http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=1756

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
using namespace std;
 char str[100010][101];
 int cmp(const void *s1,const void *s2)
{
    return(strcmp((char*)s1,(char*)s2));
}
int main()
{
    char c;

    int flag=1;
    int n=0,k=0,i;
    char str1[101];
    while(~scanf("%c",&c))
    {
        if((c>='a'&&c<='z')||(c>='A'&&c<='Z'))
        {
            flag=0;
            if(c<='Z'&&c>='A')
            str[n][k]=c+32;
            else
            str[n][k]=c;
            k++;
        }
        else
        {
            if(flag==0)
            {
               str[n][k]='\0';
                n++;
                k=0;
            }
            flag++;
        }
    }
    qsort(str,n,sizeof(str[0]),cmp);//快排对字符串排序
    strcpy(str1,str[0]);
    puts(str[0]);
    for(i=1;i<n;i++)
    {
        if(strcmp(str1,str[i])!=0)
        {
            puts(str[i]);
            strcpy(str1,str[i]);
        }
    }
    return 0;
}