Add: java.util.List implements quick sort algorithm

Author: Anilople

src/test/java/com/github/anilople/javajvm/testcode/container/ListTest.java

@@ -6,7 +6,9 @@
 import org.junit.jupiter.api.Test;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -17,6 +19,68 @@
  */
 class ListTest {
 
+    public static void main(String[] args) {
+        runQuickSort();
+    }
+
+    static <T> List<T> concat(List<T> ... lists) {
+        List<T> all = new ArrayList<>();
+        for(List<T> list : lists) {
+            all.addAll(list);
+        }
+        return all;
+    }
+
+    static <T extends Comparable<T>> List<T> quickSort(List<T> list) {
+        Objects.requireNonNull(list);
+        if(list.size() <= 1) {
+            return new ArrayList<>(list);
+        }
+
+        List<T> smaller = new ArrayList<>();
+        List<T> equal = new ArrayList<>();
+        List<T> bigger = new ArrayList<>();
+
+        T midValue = list.get(0);
+        for(T now : list) {
+            if(now.compareTo(midValue) < 0) {
+                smaller.add(now);
+            } else if(now.compareTo(midValue) == 0) {
+                equal.add(now);
+            } else {
+                bigger.add(now);
+            }
+        }
+
+        return concat(
+                quickSort(smaller),
+                equal,
+                quickSort(bigger)
+        );
+    }
+
+    private static void runQuickSort() {
+        List<Integer> list = Arrays.asList(
+                5, -3, 1, 200, 0, -10, 100, 2
+        );
+        System.out.println("before sort: " + list);
+        List<Integer> sorted = quickSort(list);
+        System.out.println("after sort: " + sorted);
+    }
+
+    @Test
+    void runQuickSortTest() {
+        JvmThreadRunner jvmThreadRunner = new JvmThreadRunner(
+                JvmThreadFactory.createFromStaticMethod(
+                        this.getClass(),
+                        "runQuickSort",
+                        "()V"
+                )
+        );
+
+        jvmThreadRunner.run();
+    }
+
     static void add() {
         List<Integer> list = new ArrayList<>();
         list.add(1);