7.11. More Code Practice with Arrays

Create a method sum13(nums) that takes an array of integers, nums and returns the sum of the numbers in the array. However, the number 13 is very unlucky, so do not add it or the number that comes immediately after a 13 to the sum. Return 0 if nums is an empty array.

Example Input

Expected Output

sum13({13, 1, 2})

2

sum13({1,13})

1

sum13({4, 13, 8})

4

sum13({13, 1, 13, 3, 2})

2

sum13({})

0

Example Input	Expected Output
`sum13({13, 1, 2})`	`2`
`sum13({1,13})`	`1`
`sum13({4, 13, 8})`	`4`
`sum13({13, 1, 13, 3, 2})`	`2`
`sum13({})`	`0`

public class Sum13
{
   public static int sum13(int[] nums)
   {
       // ADD CODE HERE //
   }

public static void main(String[] args)
   {
      int[] nums1 = {13, 1, 2};
      System.out.println(sum13(nums1));

int[] nums2 = {1, 13};
      System.out.println(sum13(nums2));

int[] nums3 = {4, 13, 8};
      System.out.println(sum13(nums3));

int[] nums4 = {13, 1, 13, 3, 2};
      System.out.println(sum13(nums4));

int[] nums5 = {};
      System.out.println(sum13(nums5));
  }
}

====
import static org.junit.Assert.*;
import org.junit.Test;
import java.io.IOException;
import java.util.Arrays;

public class RunestoneTests extends CodeTestHelper {
    public RunestoneTests()
    {
        super();
    }

@Test
    public void testSum13() throws IOException {
         String output = getMethodOutput("main");
         String expect = "2\n1\n4\n2\n0\n";
        boolean passed = getResults(expect, output, "Expected output from main");
        assertTrue(passed);
   }
}

Create a method has22(nums) that takes an array of integers, nums and returns true if there are at least two items in the list that are adjacent and both equal to 2, otherwise return false.

Example Input	Expected Output
`has22({1, 2, 2})`	`true`
`has22({2, 1, 2})`	`false`
`has22({2, 2, 8})`	`true`
`has22({3, 3, 5})`	`false`

Create the total89(nums) method below that takes an array of integers, nums, and returns the total of the numbers in nums except for all numbers in the array between an 8 and a 9 (inclusive).

Example Input	Expected Output
`total89({1, 2})`	`3`
`total89({2, 8, 3, 9, 2})`	`4`
`total89({8, 3, 5, 9, 6})`	`6`

Create a method twoSum(nums, target) that takes an array of integers nums and an integer target and returns an array with the indices of two numbers such that they add up to target. If no two numbers add up to target, it returns an empty array. Assume that each input has exactly one solution, and you may not use the same element twice.

Example Input	Expected Output
`twoSum({2,7,11,15}, 9)`	`{0, 1}`
`twoSum({2,7,11,15}, 13)`	`{0, 2}`
`twoSum({2,7,11,15}, 5)`	`{}`

import java.util.Scanner;
import java.util.Arrays;

public class TwoSum
{
   public static int[] twoSum(int[] nums, int target)
   {
       // ADD CODE HERE //
   }

public static void main(String[] args)
   {
     int[] nums = {2, 7, 11, 15};
     int target = 9;
     System.out.println(Arrays.toString(twoSum(nums, target)));
     target = 13;
     System.out.println(Arrays.toString(twoSum(nums, target)));
     target = 5;
     System.out.println(Arrays.toString(twoSum(nums, target)));
   }
}

====
import static org.junit.Assert.*;
import org.junit.Test;
import java.io.IOException;
import java.util.Arrays;

public class RunestoneTests extends CodeTestHelper {
    public RunestoneTests()
     {
        super();
    }

@Test
    public void testTwoSum() throws IOException {
         String output = getMethodOutput("main");
         String expect = "{0, 1}, {0, 2}, {}";
        boolean passed = getResults(expect, output, "Expected output from main");
        assertTrue(passed);

}
 }

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Before you keep reading...

7.11. More Code Practice with Arrays¶