给定一个按照升序排列的整数数组 nums，和一个目标值 target。找出给定目标值在数组中的开始位置和结束位置。
你的算法时间复杂度必须是 O(log n) 级别。
如果数组中不存在目标值，返回 [-1, -1]。
示例 1:
输入: nums = [5,7,7,8,8,10], target = 8
输出: [3,4]
示例 2:
输入: nums = [5,7,7,8,8,10], target = 6
输出: [-1,-1]
class Solution {
public:
int left(vector<int>& nums,int target)
{
int l = 0;
int r = nums.size()-1;
while(l <= r)
{
int mid = (l + r)/2;
if(target == nums[mid])
{
if(mid == 0 || target > nums[mid - 1])
return mid;
r = mid - 1;
}
else if(nums[mid] < target)
l = mid + 1;
else if(nums[mid] > target)
r = mid - 1;
}
return -1;
}
int right(vector<int>& nums,int target)
{
int l = 0;
int r = nums.size()-1;
while(l <= r)
{
int mid = (l + r)/2;
if(target == nums[mid])
{
if(mid == nums.size() - 1 || target < nums[mid + 1])
return mid;
l = mid + 1;
}
else if(nums[mid] < target)
l = mid + 1;
else if(nums[mid] > target)
r = mid - 1;
}
return -1;
}
vector<int> searchRange(vector<int>& nums, int target) {
int l = left(nums,target);
int r = right(nums,target);
vector<int> vec;
vec.push_back(l);
vec.push_back(r);
return vec;
}
};
