poj 2039 To and Fro

 给一组字符窜，一行n个，按下面形式书写，按列打

t o i o y
h p k n n
e l e a i
r a h s g
e c o n h
s e m o t
n l e w x

Sample Input

5
toioynnkpheleaigshareconhtomesnlewx
3
ttyohhieneesiaabss
0
Sample Output

theresnoplacelikehomeonasnowynightx
thisistheeasyoneab

 

#include <stdio.h>
#include<string.h>
int main(int argc, char *argv[])
{
	int i,j,n;
	char ch[30][300],ch1[9000];
	while(scanf("%d",&n) && n)
	{
		scanf("%s",ch1);
		int len=strlen(ch1);
 		int t=len/n;
 		int cas=0;
 		for (i=0;i<t;i++)
	    {
 		   if((i+1)%2!=0)//储存 
			{
				for (j=0;j<n;j++)
				 ch[i][j]=ch1[cas++];
			}
			else 
			{
				for (j=n-1;j>=0;j--)
				   ch[i][j]=ch1[cas++];
			}	
 		} 
		 for (i=0;i<n;i++)//按列打 
		   for (j=0;j<t;j++)
		     printf("%c",ch[j][i]);   
		 printf("\n"); 
	}
	return 0;
}