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]
Output: true
Explanation: Possible partition [1,1],[2,2],[3,3],[4,4]
Example 2: Input: [1,1,1,2,2,2,3,3]
Output: false
Explanation: No possible partition.
Example 3: Input: [1]
Output: false
Explanation: No possible partition.
Example 4: Input: [1,1]
Output: true
Explanation: Possible partition [1,1]
Example 5: Input: [1,1,2,2,2,2]
Output: true
Explanation: Possible partition [1,1],[2,2],[2,2] Note: 1 <= deck.length <= 10000
0 <= deck[i] < 10000
这道题仔细分析之后会得到X 一定得能被deck.length整除，也一定得被每个元素出现的次数整除，才能return true
class Solution {
public boolean hasGroupsSizeX(int[] deck) {
if(deck == null || deck.length < 2){
return false;
}
int min = Integer.MAX_VALUE;
Map<Integer, Integer> map = new HashMap<>();
for(int num : deck){
map.put(num, map.getOrDefault(num,0)+1);
}
for(int x = 2 ; x<=deck.length; x++){
if(deck.length % x != 0){
continue;
}
int count = 0;
for(int key : map.keySet()){
count++;
if(map.get(key) % x != 0){
break;
}
if(count == map.size()){
return true;
}
}
}
return false;
}
}