ZOJ 1698 Easier Done Than Said?

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <vector>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <functional>
#include <string>
#include <map>
using namespace std;
bool isvowels(char c)
{
    if(c=='a'||c=='e'||c=='i'||c=='o'||c=='u')
        return true;
    return false;
}
int main()
{
    bool r1,r2,r3;
    char str[100];
    while(gets(str))
    {
        if(strcmp(str,"end")==0)
            break;
        int len=strlen(str);
        r1=false;
        r2=r3=true;
        for(int i=0;i<len;i++)
        {
            if(str[i]=='a'||str[i]=='e'||str[i]=='i'||str[i]=='o'||str[i]=='u')
                r1=true;
            if(i+2<len)
            {
                if(isvowels(str[i])&&isvowels(str[i+1])&&isvowels(str[i+2]))
                    r2=false;
                if(!isvowels(str[i])&&!isvowels(str[i+1])&&!isvowels(str[i+2]))
                    r2=false;
            }
            if(i+1<len && !(str[i]=='e'||str[i]=='o') )
            {
                if(str[i]==str[i+1])
                    r3=false;
            }
        }
        if(r1&&r2&&r3)
            printf("<%s> is acceptable.\n",str);
        else
            printf("<%s> is not acceptable.\n",str);
    }

    return 0 ;
}