Search for a range, 在一个可能有重复元素的有序序列里找到指定元素的起始和结束位置

public int[] searchRange(int[] nums, int target)
    {
        if(nums == null || nums.length == 0)
        {
            return null;
        }
        int[] arr = {-1,-1};
        binarySearch(nums, 0, nums.length - 1, target, arr);
        return arr;
    }
    
    public void binarySearch(int[] nums, int left, int right, int target, int[] arr)
    {
        int mid = (left + right)/2;
        if(left > right)
        {
            return;
        }
        if(nums[left] == target && nums[right] == target)//特例
        {
            arr[0] = left;
            arr[1] = right;
            return;
        }
        if(nums[mid] == target)
        {
            int templ = mid, tempr = mid;
            while(templ>=left && nums[templ]==target)
            {
                templ --;
            }
            arr[0] = templ+1;
            while(tempr<=right && nums[tempr]==target)
            {
                tempr ++;
            }
            arr[1] = tempr-1;
        }
        else if(nums[mid] < target)
        {
            binarySearch(nums, mid + 1, right, target, arr);
        }
        else
        {
            binarySearch(nums, left, mid - 1, target, arr);
        }
    }