Add insertion sort code

jbee37142 · jbee37142 · commit b54673895647 · 2017-06-04T16:13:15.000+09:00
diff --git a/src/test/java/sort/InsertionSort.java b/src/test/java/sort/InsertionSort.java
@@ -0,0 +1,45 @@
+package sort;
+
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+public class InsertionSort {
+
+    /*
+        TASK
+        Insertion sort를 구현한다.
+     */
+
+    @Test
+    public void test() {
+        int[] arr1 = {};
+        int[] sortedArr1 = {};
+        assertThat(solution(arr1), is(sortedArr1));
+        int[] arr2 = {6,4,1,8,9,2,7,5,3};
+        int[] sortedArr2 = {1,2,3,4,5,6,7,8,9};
+        assertThat(solution(arr2), is(sortedArr2));
+        int[] arr3 = {1};
+        int[] sortedArr3 = {1};
+        assertThat(solution(arr3), is(sortedArr3));
+    }
+
+    public int[] solution(int[] arr) {
+        if (arr == null) return null;
+        int temp;
+        for (int i = 1; i < arr.length; i++) {
+            temp = arr[i];
+            int k;
+            for (k = i - 1; k >= 0; k--) {
+                if (temp >= arr[k]) {
+                    break;
+                }
+                arr[k + 1] = arr[k];
+            }
+            arr[k + 1] = temp;
+        }
+
+        return arr;
+    }
+}
