24 Game

Problem statement

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 parentheses '(' and ')' to get the value 24.

You are restricted with the following rules:

• The division operator '/' represents real division, not integer division.
  • For example, 4 / (1 - 2 / 3) = 4 / (1 / 3) = 12.
• Every operation done is between two numbers. In particular, we cannot use '-' as a unary operator.
  • For example, if cards = [1, 1, 1, 1], the expression "-1 - 1 - 1 - 1" is not allowed.
• You cannot concatenate numbers together
  • For example, if cards = [1, 2, 1, 2], the expression "12 + 12" is not valid.

Return true if you can get such expression that evaluates to 24, and false otherwise.

Example 1:

Input: cards = [4,1,8,7]Output: trueExplanation: (8-4) * (7-1) = 24

Example 2:

Input: cards = [1,2,1,2]Output: false

Constraints:

• cards.length == 4
• 1 <= cards[i] <= 9

My solution

/**
 * @param {number[]} cards
 * @return {boolean}
 */
var judgePoint24 = function(cards) {
    cards = cards.map(card => Number(card.toFixed(4)))
    
    const computeTwoNums = (num1, num2) => {
        return [num1 + num2, num1 - num2, num2 - num1, num1 * num2, num1/num2, num2/num1];
    };
    
    function dfs(list) {
        let size = list.length;
        if (size === 1) {
            if (Math.abs(list[0] - 24) < 0.001) {
                return true
            } else {
                return false;
            }
        }
        
        for (let i = 0; i < size; i++) {
            for (let j = i + 1; j < size; j++) {
                let nextRound = [];
                for (let k = 0; k < size; k++) {
                    if (k !== i && k !== j) {
                        nextRound.push(list[k])
                    }
                }
                
                for (const val of computeTwoNums(list[i], list[j])) {
                    nextRound.push(val)
                    if (dfs(nextRound)) {
                        return true;
                    } else {
                        nextRound.pop()
                    }
                }
            }
        }
        
        return false;
    }
    
    return dfs(cards)
};