Java Array Exercises: Find the sum of the two elements of a given array which is equal to a given integer
Java Array: Exercise-35 with Solution
Write a Java program to find the sum of the two elements of a given array which is equal to a given integer.
Sample array: [1,2,4,5,6]
Target value: 6.
Pictorial Presentation:

Sample Solution:
Java Code:
import java.util.*;
public class Exercise35
{
public static ArrayList<Integer> two_sum_array_target(final List<Integer> a, int b) {
HashMap<Integer, Integer> my_map = new HashMap<Integer, Integer>();
ArrayList<Integer> result = new ArrayList<Integer>();
result.add(0);
result.add(1);
for(int i = 0; i < a.size(); i++){
if(my_map.containsKey(a.get(i))){
int index = my_map.get(a.get(i));
result.set(0, index );
result.set(1, i );
break;
}
else{
my_map.put(b - a.get(i), i);
}
}
return result;
}
public static void main(String[] args){
ArrayList<Integer> my_array = new ArrayList<Integer>();
my_array.add(1);
my_array.add(2);
my_array.add(4);
my_array.add(5);
my_array.add(6);
int target = 6;
ArrayList<Integer> result = two_sum_array_target(my_array, target);
for(int i : result)
System.out.print("Index: "+i + " ");
}
}
Sample Output:
Index: 1 Index: 2
Flowchart:

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Previous: Write a Java program to find the length of the longest consecutive elements sequence from a given unsorted array of integers.
Next: Write a Java program to find all the unique triplets such that sum of all the three elements [x, y, z (x ≤ y ≤ z)] equal to a specified number.
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Java: Tips of the Day
countOccurrences
Counts the occurrences of a value in an array.
Use Arrays.stream().filter().count() to count total number of values that equals the specified value.
public static long countOccurrences(int[] numbers, int value) { return Arrays.stream(numbers) .filter(number -> number == value) .count(); }
Ref: https://bit.ly/3kCAgLb
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