diff --git a/big-o/src/main/java/com/josdem/algorithms/HalfSquareRunner.java b/big-o/src/main/java/com/josdem/algorithms/HalfSquareRunner.java
new file mode 100644
index 0000000..783a992
--- /dev/null
+++ b/big-o/src/main/java/com/josdem/algorithms/HalfSquareRunner.java
@@ -0,0 +1,28 @@
+package com.josdem.algorithms;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.logging.Logger;
+
+/*  Type: Square Time Algorithms – O(n^2/2)
+    Description: Half-square increment amount of time based on collection size
+ */
+
+public class HalfSquareRunner {
+    private final Logger log = Logger.getLogger(this.getClass().getName());
+    public List<Integer> getTargetNumbers(List<Integer> numbers, int target) {
+        List<Integer> result = new ArrayList<>();
+        for(int i=0; i < numbers.size(); i++){
+            for(int j = i + 1; j < numbers.size(); j++){
+                int a = numbers.get(i);
+                int b = numbers.get(j);
+                if (a + b == target){
+                    result.add(a);
+                    result.add(b);
+                    log.info(a + "," + b);
+                }
+            }
+        }
+        return result;
+    }
+}
diff --git a/big-o/src/main/java/com/josdem/algorithms/SquareTimeRunner.java b/big-o/src/main/java/com/josdem/algorithms/SquareTimeRunner.java
index 0c78054..4c929ee 100644
--- a/big-o/src/main/java/com/josdem/algorithms/SquareTimeRunner.java
+++ b/big-o/src/main/java/com/josdem/algorithms/SquareTimeRunner.java
@@ -2,6 +2,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.logging.Logger;
 
 /*  Type: Square Time Algorithms – O(n^2)
     Description: Square increment amount of time based on collection size
@@ -9,6 +10,8 @@
 
 public class SquareTimeRunner {
 
+    private final Logger log = Logger.getLogger(this.getClass().getName());
+
     public List<Integer> getTargetNumbers(List<Integer> numbers, int target) {
         List<Integer> result = new ArrayList<>();
         numbers.forEach(a -> {
@@ -16,6 +19,7 @@ public List<Integer> getTargetNumbers(List<Integer> numbers, int target) {
                 if (a + b == target) {
                     result.add(a);
                     result.add(b);
+                    log.info(a + "," + b);
                 }
             });
         });
diff --git a/big-o/src/test/java/com/josdem/algorithms/HalfSquareRunnerTest.java b/big-o/src/test/java/com/josdem/algorithms/HalfSquareRunnerTest.java
new file mode 100644
index 0000000..80e97ea
--- /dev/null
+++ b/big-o/src/test/java/com/josdem/algorithms/HalfSquareRunnerTest.java
@@ -0,0 +1,22 @@
+package com.josdem.algorithms;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class HalfSquareRunnerTest {
+
+    private final HalfSquareRunner halfSquareRunner = new HalfSquareRunner();
+
+    @Test
+    @DisplayName("show half-square algorithm")
+    void shouldTestHalfSquare(){
+        List<Integer> numbers = List.of(0, 1, 2, 3, 4, 5, 6, 7, 8, 9);
+        List<Integer> expectedNumbers = List.of(0, 5, 1, 4, 2, 3);
+        int target = 5;
+        assertEquals(expectedNumbers, halfSquareRunner.getTargetNumbers(numbers, target), "should get numbers from the array");
+    }
+}