Count Odd Numbers in an Interval Range - Problem
Given two non-negative integers low and high, return the count of odd numbers between low and high (inclusive).
An odd number is any integer that is not divisible by 2. For example, 1, 3, 5, 7, 9 are odd numbers.
Example: If low = 3 and high = 7, the numbers in range are [3, 4, 5, 6, 7]. The odd numbers are 3, 5, 7, so the answer is 3.
Input & Output
Example 1 — Basic Range
$
Input:
low = 3, high = 7
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Output:
3
💡 Note:
Numbers in range [3,4,5,6,7]. Odd numbers are 3, 5, 7, so count is 3.
Example 2 — Even Range
$
Input:
low = 8, high = 10
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Output:
1
💡 Note:
Numbers in range [8,9,10]. Only 9 is odd, so count is 1.
Example 3 — Single Number
$
Input:
low = 1, high = 1
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Output:
1
💡 Note:
Range contains only 1, which is odd, so count is 1.
Constraints
- 0 ≤ low ≤ high ≤ 109
Visualization
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Understanding the Visualization
1
Input Range
Given low=3, high=7
2
Identify Odds
Find odd numbers in [3,4,5,6,7]
3
Count Result
Return count of odd numbers
Key Takeaway
🎯 Key Insight: Use mathematical formula (high+1)/2 - low/2 for instant calculation instead of iteration
💡
Explanation
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