Array:给定一个数组，返回出现次数超过1/2次的元素

public static int majorityElement(int[] nums) {
        if (nums==null||nums.length==0) {
            return 0;
        }
        if (nums.length==1) {
            return nums[0];
        }
        HashMap<Integer, Integer> hashMap = new HashMap<Integer, Integer>();
        for (int i = 0; i < nums.length; i++) {
            if (hashMap.containsKey(nums[i])) {
                int count = hashMap.get(nums[i])+1;
                hashMap.put(nums[i], count);
                if (count>nums.length/2) {
                    return nums[i];
                }
            } else {
                hashMap.put(nums[i], 1);
            }
        }
        
        return -1;
    }