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FrequencyQueries.java
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FrequencyQueries.java
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// https://www.hackerrank.com/challenges/frequency-queries/problem
package dictionaries;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
public class FrequencyQueries {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
Map<Integer, Integer> elements = new HashMap<>();
Map<Integer, Integer> frequencies = new HashMap<>();
int queries = scanner.nextInt();
while (queries-- > 0) {
int operation = scanner.nextInt();
int element = scanner.nextInt();
int occurrences = elements.getOrDefault(element, 0);
int frequency = frequencies.getOrDefault(occurrences, 0);
if (operation == 1) {
elements.put(element, occurrences + 1);
frequencies.put(occurrences, frequency == 0 ? 0 : frequency - 1);
frequencies.put(occurrences + 1, frequencies.getOrDefault(occurrences + 1, 0) + 1);
} else if (operation == 2) {
elements.put(element, occurrences == 0 ? 0 : occurrences - 1);
frequencies.put(occurrences, frequency == 0 ? 0 : frequency - 1);
frequencies.put(occurrences - 1, frequencies.getOrDefault(occurrences - 1, 0) + 1);
} else {
System.out.println(frequencies.getOrDefault(element, 0) > 0 ? 1 : 0);
}
}
}
}