sort a linked list of 0s 1s and 2s: done

Author: Ram swaroop

src/me/ramswaroop/linkedlists/SortLinkedListOf0s1s2s.java

@@ -0,0 +1,55 @@
+package me.ramswaroop.linkedlists;
+
+import me.ramswaroop.common.SingleLinkedList;
+import me.ramswaroop.common.SingleLinkedNode;
+
+/**
+ * Created by IntelliJ IDEA.
+ *
+ * @author: ramswaroop
+ * @date: 7/5/15
+ * @time: 1:47 PM
+ */
+public class SortLinkedListOf0s1s2s {
+
+    /**
+     * Sorts {@param list} consisting of only 0s, 1s and 2s as their node values.
+     * <p/>
+     * Time complexity: O(n)
+     * Space complexity: O(1)
+     *
+     * @param list
+     */
+    public static void sort(SingleLinkedList<Integer> list) {
+        int[] count = new int[3];
+        SingleLinkedNode<Integer> curr = list.head;
+
+        // keep count of 0s, 1s and 2s
+        while (curr != null) {
+            count[curr.item]++;
+            curr = curr.next;
+        }
+
+        // make a linked list of that many 0s, 1s and 2s
+        list.clear();
+        for (int i = 0; i < count.length; i++) {
+            for (int j = 0; j < count[i]; j++) {
+                list.add(i);
+            }
+        }
+    }
+
+    public static void main(String a[]) {
+        SingleLinkedList<Integer> linkedList = new SingleLinkedList<>();
+        linkedList.add(0);
+        linkedList.add(1);
+        linkedList.add(2);
+        linkedList.add(0);
+        linkedList.add(1);
+        linkedList.add(2);
+        linkedList.add(1);
+        linkedList.printList();
+        sort(linkedList);
+        linkedList.printList();
+    }
+}