TapeEquilibrium

src/main/java/codility/p03_time_complexity/TapeEquilibrium.java

@@ -0,0 +1,25 @@
+package codility.p03_time_complexity;
+
+/*
+https://app.codility.com/programmers/lessons/3-time_complexity/tape_equilibrium/
+ */
+public class TapeEquilibrium {
+
+  /*
+  https://app.codility.com/demo/results/training2QRQ7D-TBR/
+   */
+  public int solution(int[] A) {
+    long sum = 0;
+    for (int value : A) sum += value;
+
+    long firstSum = A[0];
+    long secondSum = sum - A[0];
+    long minDifference = Math.abs(secondSum - firstSum);
+    for (int p = 1; p < A.length - 1; p++) {
+      firstSum += A[p];
+      secondSum -= A[p];
+      minDifference = Math.min(minDifference, Math.abs(secondSum - firstSum));
+    }
+    return (int) minDifference;
+  }
+}

src/test/java/codility/p03_time_complexity/PermMissingElemTest.java

@@ -6,7 +6,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class PermMissingElemTest {
-  PermMissingElem permMissingElem = new PermMissingElem();
+  PermMissingElem permMissingElem;
 
   @BeforeEach
   public void init() {

src/test/java/codility/p03_time_complexity/TapeEquilibriumTest.java

@@ -0,0 +1,23 @@
+package codility.p03_time_complexity;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class TapeEquilibriumTest {
+
+  TapeEquilibrium tapeEquilibrium;
+
+  @BeforeEach
+  public void init() {
+    tapeEquilibrium = new TapeEquilibrium();
+  }
+
+  @Test
+  public void sample1() {
+    int minimalDifference = tapeEquilibrium.solution(new int[]{3, 1, 2, 4, 3});
+    assertThat(minimalDifference).isEqualTo(1);
+  }
+
+}