Binary search

Author: ProgrammingLanguageLeader

src/algorithms/binary_search/Main.java

@@ -0,0 +1,52 @@
+package algorithms.binary_search;
+
+import java.util.Scanner;
+
+public class Main {
+    private void run() {
+        Scanner scanner = new Scanner(System.in);
+        int elementsNumber = scanner.nextInt();
+        int[] array = new int[elementsNumber];
+        for (int i = 0; i < elementsNumber; i++) {
+            array[i] = scanner.nextInt();
+        }
+        int searchElementsNumber = scanner.nextInt();
+        int[] searchElements = new int[searchElementsNumber];
+        for (int i = 0; i < searchElementsNumber; i++) {
+            searchElements[i] = scanner.nextInt();
+        }
+
+        StringBuilder outputBuilder = new StringBuilder();
+        for (int i = 0; i < searchElementsNumber; i++) {
+            int searchElementIndex = binarySearch(array, searchElements[i]);
+            outputBuilder.append(String.format("%d ", searchElementIndex + 1));
+        }
+        System.out.println(outputBuilder.toString());
+    }
+
+    private int binarySearch(int[] array, int searchElement) {
+        int left = 0;
+        int right = array.length - 1;
+        int currentIndex = (left + right) / 2;
+        while (left < right) {
+            if (searchElement == array[currentIndex]) {
+                break;
+            }
+            if (searchElement < array[currentIndex]) {
+                right = currentIndex - 1;
+            }
+            else {
+                left = currentIndex + 1;
+            }
+            currentIndex = (left + right) / 2;
+        }
+        if (array[currentIndex] == searchElement) {
+            return currentIndex;
+        }
+        return -2;
+    }
+
+    public static void main(String[] args) {
+        new Main().run();
+    }
+}