Package g0601_0700.s0679_24_game

Class Solution

  • public class Solution
extends Object
    679 - 24 Game.

    Hard

    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: true

    Explanation: (8-4) * (7-1) = 24

    Example 2:

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

    Output: false

    Constraints:

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

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • judgePoint24

        public boolean judgePoint24​(int[] nums)