PermCheck

src/main/java/codility/p04_counting_elements/PermCheck.java

@@ -0,0 +1,17 @@
+package codility.p04_counting_elements;
+
+import java.util.Arrays;
+/*
+https://app.codility.com/programmers/lessons/4-counting_elements/perm_check/
+ */
+public class PermCheck {
+  //https://app.codility.com/demo/results/trainingERTVB8-SXV/
+  public int solution(int[] a) {
+    Arrays.sort(a);
+    int i = 0;
+    while (i < a.length && a[i] == i + 1) {
+      i++;
+    }
+    return i < a.length ? 0 : 1;
+  }
+}

src/test/java/codility/p04_counting_elements/PermCheckTest.java

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+package codility.p04_counting_elements;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class PermCheckTest {
+  PermCheck permCheck;
+
+  @BeforeEach
+  public void init() {
+    permCheck = new PermCheck();
+  }
+
+  @Test
+  public void sample1() {
+    int solution = permCheck.solution(new int[]{4, 1, 3, 2});
+    assertThat(solution).isEqualTo(1);
+  }
+
+  @Test
+  public void sample2() {
+    int solution = permCheck.solution(new int[]{4, 1, 3});
+    assertThat(solution).isEqualTo(0);
+  }
+
+}