1031. Hello World for U (20)

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

#include<cstdio>
#include<cstring>
int main(){
    char str[80];
    gets(str);
    int N = strlen(str); 
    // 最重要的就是找n1，n2，n3的数量关系。 
    int n1 =(N+2)/3,n3 = n1, n2 = N - n1 - n3 +2; //n1 不是 N/3，n2还要加上一个2 
    for(int i = 0; i < n1-1; i++){
        printf("%c",str[i]);
        for(int j = 1; j < n2-1; j++){
            printf(" ");
        }
       printf("%c
",str[N - i -1]);
    }
    for(int k = 0; k < n2; k++){
        printf("%c",str[n1+k-1]);
        if(k == n2-1)printf("
");
    }
    return 0;
}