Question

How to check if a sequence of numbers is an Arithmetic progression (consecutive differences are the same) in Java

Answer 1

import java.util.Arrays;

public class SequenceIsArithmeticProgression_Java {
    public static boolean isArithmeticProgression(int[] arr) {
        int size = arr.length;
        if (size == 1) {
            return true;
        }

        Arrays.sort(arr);

        int difference = arr[1] - arr[0];
        for (int i = 2; i < size; i++) {
            if (arr[i] - arr[i - 1] != difference) {
                return false;
            }
        }

        return true;
    }

    public static void main(String[] args) {
        int[] arr = {10, 20, 15, 5, 25, 35, 30};

        System.out.println(isArithmeticProgression(arr) ? "Yes" : "No");
    }
}


/*
run:

Yes

*/

 

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Answer 2

import java.util.HashSet;

public class SequenceIsArithmeticProgression_Java {
    public static boolean isArithmeticProgression(int[] arr) {
        HashSet<Integer> set = new HashSet<Integer>();
        int size = arr.length;
        
        int max = Integer.MIN_VALUE;
        int min = Integer.MAX_VALUE;
        for (int i : arr) {
            max = Math.max(i, max);
            min = Math.min(i, min);
            set.add(i);
        }
        
        int difference = (max - min) / (size - 1);
        int count = 0;
 
        while (set.contains(max)) {
            count++;
            max = max - difference;
        }
        
        if (count == arr.length) {
            return true;
        }
 
        return false;
    }

    public static void main(String[] args) {
        int[] arr = {10, 20, 15, 5, 25, 35, 30};

        System.out.println(isArithmeticProgression(arr) ? "Yes" : "No");
    }
}


/*
run:

Yes

*/

 

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