多数元素数组Java O(nlogn)

public class MajorityElement {
    public static int majorityElement(int[] nums) {
        // 归并排序
        mergeSort(nums, 0, nums.length - 1);
        return nums[nums.length / 2];
    }

    // 归并排序
    private static void mergeSort(int[] nums, int left, int right) {
        if (left >= right) {
            return;
        }
        int mid = (left + right) / 2;
        mergeSort(nums, left, mid);
        mergeSort(nums, mid + 1, right);
        merge(nums, left, mid, right);
    }

    // 归并
    private static void merge(int[] nums, int left, int mid, int right) {
        int[] temp = new int[right - left + 1];
        int i = left, j = mid + 1, k = 0;
        while (i <= mid && j <= right) {
            if (nums[i] <= nums[j]) {
                temp[k++] = nums[i++];
            } else {
                temp[k++] = nums[j++];
            }
        }
        while (i <= mid) {
            temp[k++] = nums[i++];
        }
        while (j <= right) {
            temp[k++] = nums[j++];
        }
        System.arraycopy(temp, 0, nums, left, temp.length);
    }

    public static void main(String[] args) {
        int[] nums = {3, 3, 4, 2, 4, 4, 2, 4, 4};
        int majority = majorityElement(nums);
        System.out.println("多数元素为：" + majority);
    }
}