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Copy pathMedianMaintenance.java
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52 lines (45 loc) · 1.58 KB
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import java.util.PriorityQueue;
import java.util.Comparator;
/*
* Dynamically maintain the median of a list of integers
*/
public class MedianMaintenance {
public static void main(String[] args) {
int[] numbers = Utils.readIntArrayFromFile("data/Median.txt");
PriorityQueue<Integer> minHeap = new PriorityQueue<Integer>(); // root is the minimum
PriorityQueue<Integer> maxHeap = new PriorityQueue<Integer>(10, new MaxComparator()); // root is the maximum
int sum = numbers[0];
if (numbers[0] < numbers[1]) {
maxHeap.add(numbers[0]);
minHeap.add(numbers[1]);
sum += numbers[0];
} else {
maxHeap.add(numbers[1]);
minHeap.add(numbers[0]);
sum += numbers[1];
}
for (int index=2; index<numbers.length; index++) {
if (numbers[index] > maxHeap.peek()) {
minHeap.add(numbers[index]);
if ((minHeap.size()-maxHeap.size())>1) {
maxHeap.add(minHeap.poll());
}
} else {
maxHeap.add(numbers[index]);
if ((maxHeap.size()-minHeap.size())>1) {
minHeap.add(maxHeap.poll());
}
}
if (maxHeap.size() >= minHeap.size())
sum += maxHeap.peek();
else
sum += minHeap.peek();
}
System.out.println(sum%numbers.length);
}
}
class MaxComparator implements Comparator<Integer> {
public int compare( Integer x, Integer y ) {
return y-x;
}
}