1031. Hello World for U (20)

题目链接：https://www.patest.cn/contests/pat-a-practise/1031
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<stdio.h>#include<string.h>int main(){    char str[81];    scanf("%s",str);    int n1,n2,n3,len;    len=strlen(str);    n1=n3=(len+2)/3;//编程小技巧，如果x+y=n，要求x<y,且x尽量逼近y,可用x=n/2方法 ，y=n-x;    n2=len+2-n1-n3;    int i,j;    for(i=0;i<n1-1;i++){        printf("%c",str[i]);        for(j=0;j<n2-2;j++){            printf(" ");        }        printf("%c",str[len-1-i]);        printf("\n");    }    for(;i<n1+n2-1;i++){        printf("%c",str[i]);    }    return 0;}