ReverseArray.java

packagegfg.Arrays;

importjava.util.Arrays;

publicclassReverseArray {

publicstaticvoidmain(String[] args) {

int[] arr = { 10, 5, 7, 30, 20 };
System.out.println("original array: " + Arrays.toString(arr));

reverse(arr);

System.out.println("reversed array: " + Arrays.toString(arr));
 }

// O(n) time | O(1) space
publicstaticvoidreverse(int[] arr) {
intfront = 0;
intback = arr.length - 1;

for (inti = 0; i < arr.length / 2; i++) {
swap(arr, front, back);
front++;
back--;
 }
 }

publicstaticvoidswap(int[] arr, inta, intb) {
inttemp = arr[a];
arr[a] = arr[b];
arr[b] = temp;
 }
}


/* output:
original array: [10, 5, 7, 30, 20]
reversed array: [20, 30, 7, 5, 10]
*/