all tasks

Task/Sorting-algorithms-Pancake-sort/Java/sorting-algorithms-pancake-sort-1.java

@@ -0,0 +1,82 @@
+public class PancakeSort
+{
+   int[] heap;
+
+   public String toString() {
+      String info = "";
+      for (int x: heap)
+         info += x + " ";
+      return info;
+   }
+
+   public void flip(int n) {
+      for (int i = 0; i < (n+1) / 2; ++i) {
+         int tmp = heap[i];
+         heap[i] = heap[n-i];
+         heap[n-i] = tmp;
+      }
+      System.out.println("flip(0.." + n + "): " + toString());
+   }
+
+   public int[] minmax(int n) {
+      int xm, xM;
+      xm = xM = heap[0];
+      int posm = 0, posM = 0;
+
+      for (int i = 1; i < n; ++i) {
+         if (heap[i] < xm) {
+            xm = heap[i];
+            posm = i;
+         }
+         else if (heap[i] > xM) {
+            xM = heap[i];
+            posM = i;
+         }
+      }
+      return new int[] {posm, posM};
+   }
+
+   public void sort(int n, int dir) {
+      if (n == 0) return;
+
+      int[] mM = minmax(n);
+      int bestXPos = mM[dir];
+      int altXPos = mM[1-dir];
+      boolean flipped = false;
+
+      if (bestXPos == n-1) {
+         --n;
+      }
+      else if (bestXPos == 0) {
+         flip(n-1);
+         --n;
+      }
+      else if (altXPos == n-1) {
+         dir = 1-dir;
+         --n;
+         flipped = true;
+      }
+      else {
+         flip(bestXPos);
+      }
+      sort(n, dir);
+
+      if (flipped) {
+         flip(n);
+      }
+   }
+
+   PancakeSort(int[] numbers) {
+      heap = numbers;
+      sort(numbers.length, 1);
+   }
+
+   public static void main(String[] args) {
+      int[] numbers = new int[args.length];
+      for (int i = 0; i < args.length; ++i)
+         numbers[i] = Integer.valueOf(args[i]);
+
+      PancakeSort pancakes = new PancakeSort(numbers);
+      System.out.println(pancakes);
+   }
+}

Task/Sorting-algorithms-Pancake-sort/Java/sorting-algorithms-pancake-sort-2.java

@@ -0,0 +1,16 @@
+$ java PancakeSort  1 2 5 4 3 10 9 8 7
+flip(0..5): 10 3 4 5 2 1 9 8 7
+flip(0..8): 7 8 9 1 2 5 4 3 10
+flip(0..2): 9 8 7 1 2 5 4 3 10
+flip(0..7): 3 4 5 2 1 7 8 9 10
+flip(0..2): 5 4 3 2 1 7 8 9 10
+flip(0..4): 1 2 3 4 5 7 8 9 10
+1 2 3 4 5 7 8 9 10
+
+$ java PancakeSort  6 7 2 1 8 9 5 3 4
+flip(0..5): 9 8 1 2 7 6 5 3 4
+flip(0..8): 4 3 5 6 7 2 1 8 9
+flip(0..1): 3 4 5 6 7 2 1 8 9
+flip(0..4): 7 6 5 4 3 2 1 8 9
+flip(0..6): 1 2 3 4 5 6 7 8 9
+1 2 3 4 5 6 7 8 9