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Copy pathMode.java
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59 lines (46 loc) · 1.5 KB
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package Maths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
/*
* Find the mode of an array of numbers
*
* The mode of an array of numbers is the most frequently occurring number in the array,
* or the most frequently occurring numbers if there are multiple numbers with the same frequency
*/
public class Mode {
public static void main(String[] args) {
/* Test array of integers */
assert (mode(new int[] {})) == null;
assert Arrays.equals(mode(new int[] {5}), new int[] {5});
assert Arrays.equals(mode(new int[] {1, 2, 3, 4, 5}), new int[] {1, 2, 3, 4, 5});
assert Arrays.equals(mode(new int[] {7, 9, 9, 4, 5, 6, 7, 7, 8}), new int[] {7});
assert Arrays.equals(mode(new int[] {7, 9, 9, 4, 5, 6, 7, 7, 9}), new int[] {7, 9});
}
/*
* Find the mode of an array of integers
*
* @param numbers array of integers
* @return mode of the array
*/
public static int[] mode(int[] numbers) {
if (numbers.length == 0) return null;
HashMap<Integer, Integer> count = new HashMap<>();
for (int num : numbers) {
if (count.containsKey(num)) {
count.put(num, count.get(num) + 1);
} else {
count.put(num, 1);
}
}
int max = Collections.max(count.values());
ArrayList<Integer> modes = new ArrayList<>();
for (int num : count.keySet()) {
if (count.get(num) == max) {
modes.add(num);
}
}
return modes.stream().mapToInt(n -> n).toArray();
}
}