PAT Advanced 1031 Hello World for U（20）

题目描述：

Given any string of N (≥5) characters, you are asked to form the characters into the shape of U. For example, helloworld can be printed as:

h  d
e  l
l  r
lowo

That is, the characters must be printed in the original order, starting top-down from the left vertical line with n1​ characters, then left to right along the bottom line with n2​ characters, and finally bottom-up along the vertical line with n3​ characters. And more, we would like U to be as squared as possible -- that is, it must be satisfied that n1​=n3​=max { k | k≤n2​ for all 3≤n2​≤N } with n1​+n2​+n3​−2=N.
Input Specification:

Each input file contains one test case. Each case contains one string with no less than 5 and no more than 80 characters in a line. The string contains no white space.
Output Specification:

For each test case, print the input string in the shape of U as specified in the description.

Sample Input:

helloworld!

Sample Output:

h   !
e   d
l   l
lowor

算法描述：模拟

题目大意：

用所给字符串按U型输出。n1和n3是左右两条竖线从上到下的字符个数，n2是底部横线从左到右的字符个数。
要求：
① n1 == n3
② n2 >= n1
③ n1为在满足上述条件的情况下的最大值

#include<iostream>
using namespace std;

int main()
{
    string str;
    cin >> str;
    int n = str.size();
    int n1 = (n + 2)/ 3 , n3 = n1, n2 = n + 2 - n1 - n3;
    for(int i = 0 ; i < n1 - 1; i++)
    {
        cout << str[i];
        for(int j = 0 ; j < n2 - 2; j++)
        {
            cout << " ";
        }
        cout << str[n - i - 1] << endl;
    }
    for(int i = 0 ; i < n2 ; i++)
        cout << str[n1 + i - 1];
    return 0;
}