Problem
Sort the values into ascending order. For an odd number of values, take the middle one. For an even number, take the arithmetic mean of the two middle values. This challenge accepts only nonempty lists.
Implement median_number(numbers).
Input
numbers: The nonempty list of values.
Output
Return the median as a number; it may end in .5.
Constraints
1 ≤ list length ≤ 100,000. Each value is an integer between −1,000,000,000 and 1,000,000,000.
Examples
Input:
numbers = [2, 8, 4, 10]
Expected output:
expected = 6.0Input:
std::vector<long long> numbers = {2, 8, 4, 10};
Expected output:
double expected = 6.0;Input:
long[] numbers = new long[] {2, 8, 4, 10};
Expected output:
double expected = 6.0;Explanation
Sorted order is 2, 4, 8, 10. The middle pair averages to (4 + 8) / 2 = 6.
Input:
numbers = [9, 1, 4]
Expected output:
expected = 4.0Input:
std::vector<long long> numbers = {9, 1, 4};
Expected output:
double expected = 4.0;Input:
long[] numbers = new long[] {9, 1, 4};
Expected output:
double expected = 4.0;Explanation
Sorted order is 1, 4, 9, whose middle value is 4.
How to approach it
Try on your own first, then open one hint at a time.
Hint 1
The median depends on sorted order, so the positions in the sorted list are what matter.
Hint 2
After sorting, use the middle element for odd length, or combine the two middle elements for even length.
Hint 3
Be careful to preserve halves when averaging two middle values, since the answer may end in .5.
Expected complexity
O(n log n) time, O(n) extra space
References
This challenge is adapted for CodeUtility. Follow the statement and constraints above.