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Java Array Exercises: Find a missing number in an array

Java Array: Exercise-24 with Solution

Write a Java program to find a missing number in an array.

Pictorial Presentation:

Java Array Exercises: Find a missing number in an array

Sample Solution:

Java Code:

import java.util.*;
public class Exercise24 {
 public static void main(String[] args) {

   int total_num;
   int[] numbers = new int[]{1,2,3,4,6,7};
   total_num = 7;
   int expected_num_sum = total_num * ((total_num + 1) / 2);
   int num_sum = 0;
   for (int i: numbers) {
    num_sum += i;
   }
       System.out.print( expected_num_sum - num_sum);
	   System.out.print("\n");
  }
 }

Sample Data: 1,2,3,4,6,7

Sample Output: 

                                                                              
5

Flowchart:

Flowchart: Java exercises: Find a missing number in an array

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Java Code Editor:

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Previous: Write a Java program to test the equality of two arrays.
Next: Write a Java program to find common elements from three sorted (in non-decreasing order) arrays.

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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