Accepts input n, outputs a grid of n surrounding n-1 ... surrounding n = 1

printing-pattern.c

#include <stdio.h>

int main(int argc, char *argv[]) {
  int input, lowest, radius, index, flag;
  input = (int) *argv[1] - 48;
  flag = 1;
  radius = input - 1;
  index = 0;
  while(1) {
    lowest = input - index;
    for(int i = input;   i> lowest; i--) {
      printf("%d ", i);
    }
    for(int i = (radius * 2) - (index * 2) + 1; i > 0; i--) {
      printf("%d ", lowest);
    }
    for(int i = lowest + 1; i <= input; i++) {
      printf("%d ", i);
    }
    printf("\n");
    index += flag;
    if(index == -1) {
      break;
    }
    if(index >= radius) {
      flag = flag * -1;
    }
  }
}