Question:

In a deck of cards, each card has an integer written on it.

Return true if and only if you can choose X >= 2 such that it is possible to split the entire deck into 1 or more groups of cards, where:

  • Each group has exactly X cards.

  • All the cards in each group have the same integer.

Example:

  1. Input: [1,2,3,4,4,3,2,1]
  2. Output: true
  3. Explanation: Possible partition [1,1],[2,2],[3,3],[4,4]
  5. Input: [1]
  6. Output: false
  7. Explanation: No possible partition.
  9. Input: [1,1]
  10. Output: true
  11. Explanation: Possible partition [1,1]
  1. Input: [1,1,1,2,2,2,3,3]
  2. Output: false
  3. Explanation: No possible partition.
  5. Input: [1,1,2,2,2,2]
  6. Output: true
  7. Explanation: Possible partition [1,1],[2,2],[2,2]

Solution:

  1. /**
  2.  * @param {number[]} deck
  3.  * @return {boolean}
  4.  */
  5. var hasGroupsSizeX = function(deck) {
  6.     // 先归类
  7.     let map = {};
  9.     for (let i=0; i<deck.length; i++) {
  10.         if (!map[deck[i]]) {
  11.             map[deck[i]] = 0
  12.         }
  13.         map[deck[i]]++;
  14.     }
  15.     // 找最小长度
  16.     let minLen;
  17.     for (let j in map) {
  18.         if (!minLen) {
  19.             minLen = map[j]
  20.         }else{
  21.             minLen = Math.min(minLen,map[j])
  22.         }
  23.     }
  24.     // 判断最小长度是否大于等于2
  25.     if (minLen<2) return false;
  26.     var getMgn = function (a,b) {
  27.         if (a % b === 0) {
  28.             return b
  29.         }
  30.         return arguments.callee(b, a % b);
  31.     }
  32.     for (let k in map) {
  33.         // 求公约数
  34.         let mgn = getMgn(map[k],minLen);
  35.         console.log(mgn,k,minLen,map[k])
  36.         if (mgn === 1) {
  37.             return false
  38.         }
  39.     }
  40.     return true
  41. };

Runtime: 60 ms, faster than 100.00% of JavaScript online submissions for X of a Kind in a Deck of Cards.