914. X of a Kind in a Deck of Cards

[Tcdian]

914. X of a Kind in a Deck of Cards

给定一副牌，每张牌上都写着一个整数。

此时，你需要选定一个数字 X，使我们可以将整副牌按下述规则分成 1 组或更多组：

每组都有 X 张牌。
组内所有的牌上都写着相同的整数。
仅当你可选的 X >= 2 时返回 true。

Example 1

Input: deck = [1,2,3,4,4,3,2,1]
Output: true
Explanation: Possible partition [1,1],[2,2],[3,3],[4,4].

Example 2

Input: deck = [1,1,1,2,2,2,3,3]
Output: false´
Explanation: No possible partition.

Example 3

Input: deck = [1]
Output: false
Explanation: No possible partition.

Example 4

Input: deck = [1,1]
Output: true
Explanation: Possible partition [1,1].

Example 5

Input: deck = [1,1,2,2,2,2]
Output: true
Explanation: Possible partition [1,1],[2,2],[2,2].

Note

• 1 <= deck.length <= 10^4
• 0 <= deck[i] < 10^4

[Tcdian]

Solution

• JavaScript Solution

/**
 * @param {number[]} deck
 * @return {boolean}
 */
var hasGroupsSizeX = function(deck) {
    const counts = new Array(10000).fill(0);
    
    for (let i = 0; i < deck.length; i++) {
        counts[deck[i]] += 1; 
    }
    
    let GCD = counts[deck[0]];
    
    for (let i = 0; i < deck.length; i++) {
        GCD = getGCD(GCD, counts[deck[i]]);
        if (GCD < 2) {
            return false;
        }
    }
    
    return true;
    
    function getGCD(a, b) {
        return a % b === 0 ? b : getGCD(b, a % b);
    }
};