Leetcode Two-point search search for a Range

Search for a Range Total accepted:21480 Total submissions:78454 My Submissions

Given a sorted array of integers, find the starting and ending position of a Given target value.

Your algorithm ' s runtime complexity must is in the order of O (log n).

If the target is not a found in the array, return [-1,-1].

For example,
Given [5, 7, 7, 8, 8, ten] and target value 8,
return [3, 4].
Test instructions: In a well-ordered array, look for the starting subscript and end subscript for a given value
Idea: two-point search
First use Lower_bound to find the starting subscript
and use Upper_bound to find the end subscript.
Lower_bound and Upper_bound Implementation see STL Source code Analysis
Complexity: Time O (log n) space O (1)

vector<int> searchrange (int a[], int n, int target) {
	int l = distance (A, lower_bound (a, a + N, target));
	int u = Distance (A, upper_bound (a, a + N, target));
	vector<int> Res;
	if (a[l]! = target) {
		res.push_back ( -1);
		Res.push_back ( -1);
	} else{
		Res.push_back (l);
		Res.push_back (u-1);
	}
	return res;
}