Question

How to check if an array is monotonic in JavaScript

Answer 1

// check adjacent array elements to determine if the array is monotone increasing (or decreasing)

function isMonotonic(array) {
    let increase = 0;
    let decrease = 0;
    
    const size = array.length;
    
    for (let i = 0; i < size - 1; i++) {
        if (array[i] > array[i + 1]) {
            increase = 1;
        }
        if (array[i] < array[i + 1]) {
            decrease = 1;
        }
        if (increase == 1 && decrease == 1) {
            return false;
        }
    }
    
    return true;
}
        
const array = [1, 3, 4, 6, 8, 9, 11, 17, 18];

console.log(isMonotonic(array));




/*
run:

true

*/

 

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