[914]. Grouping cards

link

Title Description

Greatest common divisor

1. Ideas

Each count of the number of the number that appears on mapthe.
key: Digital
value: the number of occurrences in the
case of a packet success: the number of the greatest common divisor of all the numbers appear> = 2

2. Code

class Solution {
    public boolean hasGroupsSizeX(int[] deck) {
        if(deck == null || deck.length == 0){
            return false;
        }
        HashMap<Integer,Integer> map = new HashMap<>();
        for(int i = 0; i < deck.length ;i++){
            if(!map.containsKey(deck[i])){
                map.put(deck[i],1);
            }else{
                int temp = map.get(deck[i]);
                temp++;
                map.put(deck[i],temp);
            }
        }
        int temp = map.get(deck[0]);
        for(Integer key : map.keySet()){
            temp = gcd(map.get(key),temp);
        }
        if(temp >= 2){
            return true;
        }
        return false;
    }
    
    //求两个数的最大公约数
    //辗转相除法
    private int gcd(int a ,int b){
        return a % b == 0 ? b : gcd(b,a%b);
    }
}

3. Run Results: