Is there any math function in C library to calculate MEDIAN of 'n' numbers?
A:
to get the median you can sort the array of numbers and take:
1) in case when number of items is odd - the number in the middle
2) in case when number of items is even - the average of two numbers in the middle
catwalk
2009-12-25 13:39:02
yikes, O(n log n) for a problem that can be solved in O(n)!!
Eli Bendersky
2009-12-25 15:02:51
@Eli: simplicity often trumps efficiency and I have a gut feeling that this is what OP wants
catwalk
2009-12-25 15:11:29
@catwalk: fair enough, but then it would be prudent to explicitly specify in your answer that it's the simple, not the efficient solution
Eli Bendersky
2009-12-25 15:38:19
A:
No, there is no median function in the standard C library.
Thomas Padron-McCarthy
2009-12-25 13:40:59
+3
A:
No, there is no such function in the standard C library.
However, you can implement one (or surely find code online). An efficient O(n) algorithm for finding a median is called "selection algorithm" and is related to quicksort. Read all about it here.
Eli Bendersky
2009-12-25 15:05:43
A:
To compute the median using the standard C library, use the standard library function qsort() and then take the middle element. If the array is a and has n elements, then:
qsort(a, n, sizeof(a[0]), compare);
return a[n/2];
You have to write your own compare function which will depend on the type of an array element. For details consult the man page for qsort or look it up in the index of Kernighan and Ritchie.
Norman Ramsey
2009-12-26 02:57:36