1031 Hello World for U (20分)

#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
    string s;
    cin >> s;
    int N = s.size();
    int n1=(N+2)/3, n3 = (N+2)/3;
    int n2 = N + 2 - n1 - n3;
    for(int i = 0; i<n1; ++i)
    {
        if(i == n1-1)
            for(int j = i; j<n1+n2-1; ++j)
                printf("%c",s[j]);
        else
        {
            printf("%c",s[i]);
            for(int j = 0; j<n2-2; ++j)
                printf(" ");
            printf("%c",s[N-i-1]);
        }
        printf("
");
    }
    return 0;
}