杭電ACM 2043パスワードの問題はすでにAC

#include <iostream>
#include <stdio.h>
#include <string.h>
using namespace std;
int main()
{
    char a[50];
    int m,k1,k2,k3,k4;
    unsigned i;
    cin>>m;
    getchar();
    while(m--)
    {
        k1=k2=k3=k4=0;
        cin.getline(a,50);
        if(strlen(a)<8||strlen(a)>16)
        {
            cout<<"NO"<<endl;
        }
        else
        {
            for(i=0;i<strlen(a);i++)
            {
                if(a[i]>='0'&&a[i]<='9')
                    k1=1;
                if(a[i]>='a'&&a[i]<='z')
                    k2=1;
                if(a[i]>='A'&&a[i]<='Z')
                    k3=1;
                if(a[i]=='~'||a[i]=='!'||a[i]=='@'||a[i]=='#'||a[i]=='$'||a[i]=='%'||a[i]=='^')
                    k4=1;
            }
            if(k1+k2+k3+k4>=3)
                cout<<"YES"<<endl;
            else
                cout<<"NO"<<endl;

        }
    }
    return 0;
}