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Median.java
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49 lines (45 loc) · 1.71 KB
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package com.thealgorithms.maths;
import java.util.Arrays;
/**
* Utility class for calculating the median of an array of integers.
* The median is the middle value in a sorted list of numbers. If the list has
* an even number
* of elements, the median is the average of the two middle values.
*
* <p>
* Time Complexity: O(n log n) due to sorting
* <p>
* Space Complexity: O(1) if sorting is done in-place
*
* @see <a href="https://en.wikipedia.org/wiki/Median">Median (Wikipedia)</a>
* @see <a href=
* "https://www.khanacademy.org/math/statistics-probability/summarizing-quantitative-data/mean-median-basics/a/mean-median-and-mode-review">Mean,
* Median, and Mode Review</a>
*/
public final class Median {
private Median() {
}
/**
* Calculates the median of an array of integers.
* The array is sorted internally, so the original order is not preserved.
* For arrays with an odd number of elements, returns the middle element.
* For arrays with an even number of elements, returns the average of the two
* middle elements.
*
* @param values the array of integers to find the median of (can be unsorted)
* @return the median value as a double
* @throws IllegalArgumentException if the input array is empty or null
*/
public static double median(int[] values) {
if (values == null || values.length == 0) {
throw new IllegalArgumentException("Values array cannot be empty or null");
}
Arrays.sort(values);
int length = values.length;
if (length % 2 == 0) {
return (values[length / 2] + values[length / 2 - 1]) / 2.0;
} else {
return values[length / 2];
}
}
}