【剑指Offer】II-数组中数字出现的次数 II

输入：nums = [3,4,3,3]
输出：4

输入：nums = [9,1,7,9,7,9,7]
输出：1

class Solution {
    public int singleNumber(int[] nums) {
        Map<Integer,Integer> result  = new HashMap<Integer,Integer>();

        for (int num : nums) {
           int count =  result.getOrDefault(num,0) + 1;
            result.put(num,count);
        }

        for (Map.Entry<Integer,Integer> entry : result.entrySet()) {
            if (entry.getValue() == 1) {
                return entry.getKey();
            }
        }
        return 0;
    }
}