samples/alpha-mj-exp/SortColors.mj

   1 program SortColors {
   2     // array with n objects colored red, white or blue
   3     // sort so that the same colored objects are adjacent
   4     // red, white, blue = 0, 1, 2 (values in array)
   5
   6     void sortColors(int[] nums)
   7     int p0, p1, p2, temp;
   8     {
   9         p0 = 0;
  10         p1 = 0;
  11         p2 = len(nums) - 1;
  12
  13         while (p1 <= p2) {
  14             if (nums[p1] == 0) {
  15                 temp = nums[p0];
  16                 nums[p0] = nums[p1];
  17                 nums[p1] = temp;
  18                 p0 = p0 + 1;
  19                 p1 = p1 + 1;
  20             } else if (nums[p1] == 1) {
  21                 p1 = p1 + 1;
  22             } else {
  23                 temp = nums[p1];
  24                 nums[p1] = nums[p2];
  25                 nums[p2] = temp;
  26                 p2 = p2 - 1;
  27             }
  28         }
  29     }
  30
  31     void printArr(int[] nums)
  32     int i;
  33     {
  34         i = 0;
  35         print('\n');
  36         print('[');
  37         while (i < len(nums)) {
  38             print(nums[i], 2);
  39             i++;
  40         }
  41         print(']', 2);
  42     }
  43
  44     void main()
  45     int n, i;
  46     int[] nums;
  47     {
  48         print('n');
  49         print('?');
  50         read(n);
  51         nums = new int[n];
  52         i = 0;
  53         while (i < n) {
  54             print('n');
  55             print(i);
  56             print('?');
  57             print(' ');
  58             read(nums[i]);
  59             i++;
  60         }
  61         sortColors(nums);
  62         printArr(nums);
  63     }
  64 }