题解 | #Hello World for U#

#include<iostream>
#include<algorithm>
using namespace std;
int main()
{
    string str;
    cin >> str;
    int len = str.size();
    int n1 = len / 3;
    int n3 = len / 3;
    int n2 = len - (len / 3) * 2;
    if (n1 == n2) {
        n1 = n1 - 1;
        n3 = n3 - 1;
        n2 = n2 + 2;
    }
    string str1 = str.substr(0,n1);
    string str2 = str.substr(n1,n2);
    string str3 = str.substr(n1 + n2,n3);
    reverse(str3.rbegin(), str3.rend());
    for (int i = 0; i < n1; ++i) {
        cout << str1.at(i);
        for (int j = 0; j < n2 - 2; ++j)
            cout << " ";
        cout << str3.at(i);
        cout << endl;
    }
    cout << str2;
}