1031. Hello World for U (20)-PAT甲级真题

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

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

分析:假设n = 字符串长度 + 2,因为2 * n1 + n2 = n,且要保证n2 >= n1, n1尽可能地大,分类讨论:
1. 如果n % 3 == 0,n正好被3整除,直接n1 == n2 == n3;
2. 如果n % 3 == 1,因为n2要比n1大,所以把多出来的那1个给n2
3. 如果n % 3 == 2, 就把多出来的那2个给n2
所以得到公式:n1 = n / 3,n2 = n / 3 + n % 3
把它们存储到二维字符数组中,一开始初始化字符数组为空格,然后按照u型填充进去,最后输出这个数组u~~

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