1007. To and Fro

Input

There will be multiple input sets. Input for each set will consist of two lines. The first line will contain an integer in the range 2 . ..20 indicating the number of columns used. The next line is a string of up to 200 lower case letters. The last input set is followed by a line containing a single 0, indicating end of input.

Output

Each input set should generate one line of output, giving the original plaintext message, with no spaces.

Sample Input

5
toioynnkpheleaigshareconhtomesnlewx
3
ttyohhieneesiaabss
0

Sample Output

theresnoplacelikehomeonasnowynightx
thisistheeasyoneab

代码实现:

#include<stdio.h>#include<string.h>int main() {  int i, j, n, k = 1;  char s[1000];  char a[200][200] = {0};  while (1) {    scanf("%d", &n);    if (n == 0 ) break;    scanf("%s", s);    k = 1;    for (i = 0; i < strlen(s)/n; i++) {      if (k == 1) {      for (j = 0; j < n; j++) {      a[i][j] = s[i*n + j];      }      k = k*(-1);      } else {      for (j = n - 1; j >= 0 ; j--) {      a[i][j] = s[i*n + n - j - 1];      }      k = k*(-1);      }    }    for (j = 0; j < n; j++) {      for (i = 0; i < strlen(s)/n; i++)      printf("%c", a[i][j]);    }    printf("\n");  }  return 0;}