package LeetCode_914 /** * 914. X of a Kind in a Deck of Cards * https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards/description/ * * 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: 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. Constraints: 1 <= deck.length <= 10^4 0 <= deck[i] < 10^4 * */ class Solution { /* * solution: HashMap, calculate each deck of group, then check if can has exactly X cards * Time complexity:O(n), Space complexity:O(n) * */ fun hasGroupsSizeX(deck: IntArray): Boolean { if (deck == null || deck.isEmpty()) { return false } val map = HashMap<Int, Int>() for (item in deck) { map.put(item, map.getOrDefault(item, 0) + 1) } var countInGroup = Int.MAX_VALUE for (item in map) { countInGroup = Math.min(countInGroup, item.value) } //if each group cannot exactly 2 cards, return false if (countInGroup < 2) { return false } //keep check if each card has save group size for (i in 2 .. countInGroup) { var can = true for (item in map) { if (item.value % i != 0) { can = false break } } if (can) { return true } } return false } }