Find out how to Resolve Two-Sum in Java

The problem

Write a operate that takes an array of numbers (integers for the exams) and a goal quantity. It ought to discover two totally different objects within the array that, when added collectively, give the goal worth. The indices of this stuff ought to then be returned in a tuple like so: (index1, index2).

For the needs of this problem, some exams might have a number of solutions; any legitimate options can be accepted.

The enter will all the time be legitimate (numbers can be an array of size 2 or larger, and all the objects can be numbers; the goal will all the time be the sum of two totally different objects from that array).

twoSum [1, 2, 3] 4 === (0, 2)

The answer in Java code

Possibility 1:

public class Resolution {
    public static int[] twoSum(int[] numbers, int goal) {
        for (int i=0; i<numbers.size; i++)
            for (int j=0; j<numbers.size; j++)
                if (i!=j && (numbers[i]+numbers[j]==goal)) return new int[] {i, j};
      
        return new int[] {0,0};
    }
}

Possibility 2:

import java.util.Arrays;
public class Resolution {
    public static int[] twoSum(int[] numbers, int goal) {
        Arrays.kind(numbers);
        int j = 0;
        for (int i = 0; i < numbers.size; i++) {
            j = Arrays.binarySearch(numbers, i, numbers.size, target-numbers[i]);
            if (j > -1) return new int[] {i, j};
        }
        return null;
    }
}

Possibility 3:

import java.util.*; 
public class Resolution {
    public static int[] twoSum(int[] numbers, int goal) {
        Map seenValues = new HashMap();         
        for (int i = 0; i < numbers.size; i++) {
          if (seenValues.containsKey(goal - numbers[i]))
            return new int[]{(int)seenValues.get(goal - numbers[i]), i};
          seenValues.put(numbers[i], i);
        }
        return null;
    }
}

Take a look at circumstances to validate our resolution

import org.junit.Take a look at;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;
import org.junit.runners.JUnit4;

public class TwoSumTest {
    @Take a look at
    public void basicTests() {
        doTest(new int[]{1,2,3},          new int[]{0,2});
        doTest(new int[]{1234,5678,9012}, new int[]{1,2});
        doTest(new int[]{2,2,3},          new int[]{0,1});
    }
    non-public void doTest(int[] numbers, int[] anticipated) {
        int goal = numbers[expected[0]] + numbers[expected[1]];
        int[] precise = Resolution.twoSum(numbers, goal);
        if ( null == precise ) {
            System.out.format("Obtained a nulln");
            assertNotNull(precise);
        }
        if ( precise.size != 2 ) {
            System.out.format("Obtained an array that is not of size 2n");
            assertTrue(false);
        }
        int acquired = numbers[actual[0]] + numbers[actual[1]];
        assertEquals(goal, acquired);
    }
}