Authors:
Michael T. Goodrich, Roberto Tamassia, Michael H. Goldwasser
Chapter:
Java Primer
Exercise:
Exercises
Question:14 | ISBN:9781118771334 | Edition: 6
Question
Write a pseudocode description of a method that reverses an array of n integers, so that the numbers are listed in the opposite order than they were before, and compare this method to an equivalent Java method for doing the same thing.
Answer
Pseudocode:
step 1: initilize array using new int[] { }
step 2: use for loop to print orginal array
for int i = 0; i < arraylength; i increment
step 3: print the array using print command
print array in reverse order
step 4: run the array in loop
step 5: inilizie i to point last element in the array
for int i = arraylength-1; i >= 0 ; i decrement
step 6: print the array
//java code to write array in reverse
package java_problems_datastructures;
public class ReverseAnArray {
// initialize array
static int[] arrayOfIntegers = {2,5,8,56,23,9,11};
// Driver method
public static void main(String args[]) {
// call the method
reverseArray(arrayOfIntegers);
}
public static void reverseArray(int[] arr) {
// Print the array as it is
System.out.println("Array before reverse operation : ");
for(int i = 0 ; i < arrayOfIntegers.length; i++) {
System.out.print(arrayOfIntegers[i] + " ");
}
// Print the array reading from last index first
System.out.println(" \nArray after reverse operation : ");
for(int i = arrayOfIntegers.length-1 ; i>= 0 ; i--) {
System.out.print(arrayOfIntegers[i]+ " ");
}
}
}
Output:
Array before reverse operation :
2 5 8 56 23 9 11
Array after reverse operation :
11 9 23 56 8 5 2