Added SelectionSort.java Please add Hactoberfest Accepted tag and merge it

java/SelectionSort.java

@@ -0,0 +1,37 @@
+import java.util.*;
+
+public class SelectionSort {
+    public static void main(String[] args) {
+        Scanner scan = new Scanner(System.in);
+        int n = scan.nextInt();
+        int[] arr = new int[n];
+        for(int i = 0; i < n; i++)
+            arr[i] = scan.nextInt();
+        selectionSort(arr);
+        System.out.println(Arrays.toString(arr));
+    }
+
+    public static void selectionSort(int[] arr) {
+        for(int i = 0; i < arr.length; i++) {
+            // find the max item in the remaining array and swap with the correct index
+            int last = arr.length - i - 1;
+            int maxIndex = getMaxIndex(arr, 0, last);
+            swap(arr, maxIndex, last);
+        }
+    }
+
+    public static int getMaxIndex(int[] arr, int start, int end) {
+        int max = start;
+        for(int i = start; i <= end; i++) {
+            if(arr[i] > arr[max])
+                max = i;
+        }
+        return max;
+    }
+
+    public static void swap(int[] arr, int i, int correct) {
+        int temp = arr[i];
+        arr[i] = arr[correct];
+        arr[correct] = temp;
+    }
+}