majority number

public int (int[] nums) {
    int count = 1;
    int major = nums[0];
    for (int i = 1; i < nums.length; ++i) {
        if (count == 0) {
            major = nums[i];
        }
        if (major == nums[i])
            count++;
        else
            count--;
    }
    return major;
}

public List<Integer> (int[] nums) {
    List<Integer> ans = new ArrayList<Integer>();
    if (nums == null || nums.length == 0)
        return ans;
    int count1 = 0, count2 = 0;
    int major1 = 0, major2 = 0;
    for (int i = 0; i < nums.length; ++i) {
        if (count1 == 0) {
            major1 = nums[i];
        } else if (count2 == 0) {
            major2 = nums[i];
        }

        if (major1 == nums[i]) {
            count1++;
        } else if (major2 == nums[i])
            count2++;
        else {
            count1--;
            count2--;
        }
    }
    count1 = count2 = 0;
    for (int i : nums) {
        if (i == major1) {
            count1++;
        } else if (i == major2)
            count2++;
    }
    if (count1 > nums.length / 3)
        ans.add(major1);

    if (count2 > nums.length / 3)
        ans.add(major2);

    return ans;
}

public List<Integer> (int[] nums) {
    List<Integer> ans = new ArrayList<Integer>();
    if (nums == null || nums.length == 0)
        return ans;
    int n1 = 0, n2 = 0, c1 = 0, c2 = 0;
    for (int i : nums) {
        if (n1 == i)
            ++c1;
        else if (n2 == i)
            ++c2;
        else if (c1 == 0) {
            c1 = 1; n1 = i;
        } else if (c2 == 0) {
            c2 = 1; n2 = i;
        } else {
            --c1; --c2;
        }
    }
    c1 = 0; c2 = 0;
    for (int i : nums) {
        if (i == n1)
            ++c1;
        else if (i == n2)
            ++c2;
    }
    if (c1 > nums.length / 3)
        ans.add(n1);
    if (c2 > nums.length / 3)
        ans.add(n2);
    return ans;
}

public int majorityNumber(ArrayList<Integer> nums, int k) {
    
    HashMap<Integer, Integer> map = new HashMap<>();
    for (int i : nums) {
        if (map.containsKey(i)) {
            map.put(i, map.get(i) + 1);
        } else
            map.put(i, 1);

        if (map.size() >= k)
            remove(map);
    }
    for (int i : map.keySet()) {
        map.put(i, 0);
    }
    for (int i : nums) {
        if (map.containsKey(i))
            map.put(i, map.get(i) + 1);
    }
    int max = 0, ans = 0;
    for (int i : map.keySet()) {
        if (max < map.get(i)) {
            ans = i;
            max = map.get(i);
        }
    }
    return ans;
}

public void remove(HashMap<Integer, Integer> map) {
    Set<Integer> set = map.keySet();
    HashSet<Integer> delete = new HashSet<>();
    for (int i : set) {
        map.put(i, map.get(i) - 1);
        if (map.get(i) == 0)
            delete.add(i);
    }
    for (int i : delete) {
        map.remove(i);
    }
}