20200408——第三十四题 在排序数组中查找元素的第一个和最后一个

class Solution {
    public int[] searchRange(int[] nums, int target) {
        if(nums == null){
            return new int[]{-1,-1};
        }
        int first = find(true,nums,target);
        int last = find(false,nums,target);

        return new int[]{first,last};    

    }
    public int find(boolean bool,int[] nums,int target){
        int begin = 0 ;
        int end = nums.length-1;
        while(begin<=end){
            int mid = begin+(end-begin)/2;
            if(nums[mid] > target){
                end = mid-1;
            }else if(nums[mid] < target){
                begin = mid+1;
            }else{
                if(bool){
                    if(mid>0 && nums[mid] == nums[mid-1]){
                        end = mid-1;
                    }else{
                        return mid;
                    }
                }else{
                    if(mid <nums.length-1 && nums[mid] == nums[mid+1]){
                        begin = mid+1;
                    }else{
                        return mid;
                    }
                }
            }
        }
        return -1;
    }
}

一开始我找到第一个元素的时候，一直往后去找或者往前去找，这样不对，时间复杂度过于高了。