Data commit

Task/Longest-increasing-subsequence/Java/longest-increasing-subsequence.java

@@ -0,0 +1,40 @@
+import java.util.*;
+
+public class LIS {
+    public static <E extends Comparable<? super E>> List<E> lis(List<E> n) {
+        List<Node<E>> pileTops = new ArrayList<Node<E>>();
+        // sort into piles
+        for (E x : n) {
+	    Node<E> node = new Node<E>();
+	    node.value = x;
+            int i = Collections.binarySearch(pileTops, node);
+            if (i < 0) i = ~i;
+	    if (i != 0)
+		node.pointer = pileTops.get(i-1);
+            if (i != pileTops.size())
+                pileTops.set(i, node);
+            else
+                pileTops.add(node);
+        }
+	// extract LIS from nodes
+	List<E> result = new ArrayList<E>();
+	for (Node<E> node = pileTops.size() == 0 ? null : pileTops.get(pileTops.size()-1);
+                node != null; node = node.pointer)
+	    result.add(node.value);
+	Collections.reverse(result);
+	return result;
+    }
+
+    private static class Node<E extends Comparable<? super E>> implements Comparable<Node<E>> {
+	public E value;
+	public Node<E> pointer;
+        public int compareTo(Node<E> y) { return value.compareTo(y.value); }
+    }
+
+    public static void main(String[] args) {
+	List<Integer> d = Arrays.asList(3,2,6,4,5,1);
+	System.out.printf("an L.I.S. of %s is %s\n", d, lis(d));
+        d = Arrays.asList(0, 8, 4, 12, 2, 10, 6, 14, 1, 9, 5, 13, 3, 11, 7, 15);
+	System.out.printf("an L.I.S. of %s is %s\n", d, lis(d));
+    }
+}