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What’s your alternative solution? Challenge #51

About this series

This is series of daily JavaScript coding challenges... for both beginners and advanced users.

Each day I’m gone present you a very simple coding challenge, together with the solution. The solution is intentionally written in a didactic way using classic JavaScript syntax in order to be accessible to coders of all levels.

Solutions are designed with increase level of complexity.

Today’s coding challenge

Find the maximum number in a jagged array of numbers or array of numbers

(scroll down for solution)

Code newbies

If you are a code newbie, try to work on the solution on your own. After you finish it, or if you need help, please consult the provided solution.

Advanced developers

Please provide alternative solutions in the comments below.

You can solve it using functional concepts or solve it using a different algorithm... or just solve it using the latest ES innovations.

By providing a new solution you can show code newbies different ways to solve the same problem.


// Solution for challenge46a

var ar = [2, 4, 10, [12, 4, [100, 99], 4], [3, 2, 99], 0];

var max = findMax(ar);
println("Max  = ", max);

// Use recursion to find the maximum numeric value in an array of arrays
function findMax(ar)
    var max = -Infinity;

    // Cycle through all the elements of the array
    for(var i = 0; i < ar.length; i++)
        var el = ar[i];

        // If an element is of type array then invoke the same function
        // to find out the maximum element of that subarray
        if ( Array.isArray(el) )
            el = findMax( el );

        if ( el > max )
            max = el;

    return max;

To quickly verify this solution, copy the code above in this coding editor and press "Run".

Note: The solution was originally designed for environment, and therefore is making use of println. This is the almost equivalent of console.log in other environments. Please feel free to use your preferred coding playground / environment when implementing your solution.

Top comments (4)

jacksoncurrie profile image
Jackson Currie • Edited
const findMax = x => Math.max(...x.flat(Infinity))
miketalbot profile image
Mike Talbot ⭐

See I forget flat is in there. Nice.

miketalbot profile image
Mike Talbot ⭐ • Edited

    const maxInArray = v => Array.isArray(v) ? 
             (a,c)=>Math.max(a, maxInArray(c))
         ) : v

chrismj83 profile image
Chris Johnson • Edited
const findMax = arr => {
    const res = arr.flatMap(val => Array.isArray(val) ? findMax(val) : val).sort((a, b) => a - b);
    return res[res.length - 1];