Count Odd Numbers in an Interval Range
The problem asks to return the count of odd numbers between two given nonnegative integers low
and high
(inclusive).
Approach
To count the number of odd numbers between low
and high
, we can use the following observations:
 If both
low
andhigh
are even, then the number of odd numbers between them will be(high  low) / 2
.  If one of
low
orhigh
is odd, then the number of odd numbers between them will be(high  low) / 2 + 1
.
Combining the two cases, we can write the following function:


This code takes into account both cases by adding 1 to high
before dividing by 2 and then subtracting low
divided by 2.
Example
For low = 3
and high = 7
, the odd numbers between them are [3, 5, 7]
, so the output is 3
.
For low = 8
and high = 10
, the odd numbers between them are [9]
, so the output is 1
.
Complexity
This solution has a time complexity of O(1) and a space complexity of O(1), as it involves only simple arithmetic operations.

