You are given an integer array cards of length 4. You have four cards, each containing a number in the range [1, 9]. You should arrange the numbers on these cards in a mathematical expression using the operators ['+', '-', '*', '/'] and the parenthes

judgePoint24.js

/**
 * @param {number[]} cards
 * @return {boolean}
 */
var judgePoint24 = function(cards) {
    // Convert all numbers to floats for real division
    const nums = cards.map(num => num * 1.0);

    function backtrack(arr) {
        // Base case: only one number left, check if it's close to 24
        if (arr.length === 1) {
            return Math.abs(arr[0] - 24) < 1e-6;
        }

        // Try every pair of numbers
        for (let i = 0; i < arr.length; i++) {
            for (let j = 0; j < arr.length; j++) {
                if (i === j) continue;

                // Pick two numbers to operate on
                const a = arr[i];
                const b = arr[j];

                // Create a new array without a and b
                const rest = [];
                for (let k = 0; k < arr.length; k++) {
                    if (k !== i && k !== j) rest.push(arr[k]);
                }

                // Try all 4 operations
                const candidates = [
                    a + b,
                    a - b,
                    b - a,
                    a * b,
                    a / b,
                    b / a
                ];

                for (const result of candidates) {
                    // Recurse with the new result added to the remaining numbers
                    if (backtrack([...rest, result])) return true;
                }
            }
        }

        return false;
    }

    return backtrack(nums);
};