Check array in JS - is list sorted? [duplicate]

Question

I need to create a program that checks the list in the array is sorted. I have three input data:

1,2,3,4,5

1,2,8,9,9

1,2,2,3,2

So here is my code:

let sorts = +gets(); // 3 let list = [];  for (let i = 0; i < sorts; i++) {     list[i] = gets().split(',').map(Number); // The Array will be: [ [ 1, 2, 3, 4, 5 ], [ 1, 2, 8, 9, 9 ], [ 1, 2, 2, 3, 2 ] ] }  for (let i = 0; i < list[i][i].length; i++){     if (list[i][i] < list[i][i +1]) {         print('true');     } else {         print('false');     } } 

I need to print for all lists on new line true or false. For this example my output needs to be:

true

true

false

I have no idea how to resolve this.

Answer 1

How about something like this:

!![1,2,3,4,5].reduce((n, item) => n !== false && item >= n && item) // true  !![1,2,8,9,9].reduce((n, item) => n !== false && item >= n && item) // true   !![1,2,2,3,2].reduce((n, item) => n !== false && item >= n && item) // false 

Reduce will literally reduce the array down to a single value - a boolean in our case.

Here, we are calling a function per iteration, the (n, item) is our function signature, it's body being n !== false && item >- n && item - we are making sure that n exists (n is our accumulator - read up!), testing if item is greater than n, and making sure item exists.

This happens for every element in your array. We then use !! to force the result into a tru boolean.

Answer 2

You can use array#every to check if each value is greater than the previous value.

const isSorted = arr => arr.every((v,i,a) => !i || a[i-1] <= v);  console.log(isSorted([1,2,3,4,5]));  console.log(isSorted([1,2,8,9,9]));   console.log(isSorted([1,2,2,3,2]));