Java Program to Multiply Corresponding Elements of Two Lists

07 Jan, 2021
Multiplying two corresponding elements implies multiplying the first element of the one list with the first element of another list and so on with the second element till the size of the list. Given 2 lists of elements, we have to multiply the corresponding elements of two lists.
This can be done in 2 ways:
Using extra spaceWithout Using extra space
Using extra space
Without Using extra space
Method 1: (Using Extra Space) – You can multiply the corresponding elements and store them in a string using the in-built function Integer.toString and print the string at last.
Java
// Java program to multiply the corresponding elements of// two list. using string in-built function  import java.util.Arrays;  class GFG {    public static void main(String[] args)    {        int a1[] = { 2, 5, -2, 10 };        int a2[] = { 3, -5, 7, 1 };          String result = "";          for (int i = 0; i < a1.length; i++) {            // converting integer to string and            // multiplying corresponding element            result += Integer.toString(a1[i] * a2[i]) + " ";        }          System.out.println(result);    }}
6 -25 -14 10
Space Complexity: O(n)
Now instead of using string we can also store the output in the new array if we want to use the result later in the program.
Java
// Java program to cmultiply the corresponding elements of// two list. using new array  import java.util.Arrays;  class GFG {    public static void main(String[] args)    {        int a1[] = { 2, 5, -2, 10 };        int a2[] = { 3, -5, 7, 1 };          int result[] = new int[a1.length];          for (int i = 0; i < a1.length; i++)         {            // multiplying corresponding element            result[i] = a1[i] * a2[i];        }          for (int i = 0; i < a1.length; i++)        {            System.out.print(result[i] + " ");        }    }}
6 -25 -14 10
Space Complexity: O(n)
Method 2: (Without using extra space)
This is the same as the above-mentioned approach. The only difference is instead of using the extra array we will use any of the 2 arrays used in input to store values of the output or after multiplication.
Java
// Java program to multiply the corresponding elements of// two list. using no extra space  import java.util.Arrays;  class GFG {    public static void main(String[] args)    {        int a1[] = { 2, 5, -2, 10 };        int a2[] = { 3, -5, 7, 1 };          for (int i = 0; i < a1.length; i++) {                        // multiplying corresponding element            // you can use any array            a1[i] = a1[i] * a2[i];        }          for (int i = 0; i < a1.length; i++) {            System.out.print(a1[i] + " ");        }    }}
6 -25 -14 10
Space Complexity: O(1) (as we do not use any other auxiliary space)
Note: Time Complexity of all the above codes is O(n).
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