Question

How to check if an array is all increasing or decreasing and the gap between numbers is 1, 2 or 3 in Java

Answer 1

public class Main {

    public static boolean isArraySortedAndValidGap(int[] arr) {
        if (arr == null || arr.length < 2) {
            return false;
        }

        boolean isIncreasing = arr[1] > arr[0];
        for (int i = 1; i < arr.length; i++) {
            int gap = Math.abs(arr[i] - arr[i - 1]);
            if (gap < 1 || gap > 3) {
                return false;
            }
            if (isIncreasing && arr[i] <= arr[i - 1]) {
                return false;
            }
            if (!isIncreasing && arr[i] >= arr[i - 1]) {
                return false;
            }
        }
        
        return true;
    }

    public static void main(String[] args) {
        int[] array1 = {1, 2, 3, 5, 8, 11, 14, 15};
        int[] array2 = {15, 14, 11, 8, 5, 3, 2, 1};
        int[] array3 = {1, 2, 3, 5, 8, 110, 14, 15};

        System.out.println(isArraySortedAndValidGap(array1)); 
        System.out.println(isArraySortedAndValidGap(array2)); 
        System.out.println(isArraySortedAndValidGap(array3)); 
    }
}



/*
run:
 
true
true
false
 
*/

 

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