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| class FrequencyTracker {
private final Map<Integer, Integer> numToFreqMap;
private final Map<Integer, Integer> freqToCountMap;
public FrequencyTracker() {
this.numToFreqMap = new HashMap<>();
this.freqToCountMap = new HashMap<>();
}
public void add(int number) {
int prevFreq = numToFreqMap.getOrDefault(number, 0);
int currFreq = prevFreq + 1;
numToFreqMap.put(number, currFreq);
updateFreqCount(prevFreq, -1);
updateFreqCount(currFreq, +1);
}
private void updateFreqCount(int freq, int offset) {
int prevCount = freqToCountMap.getOrDefault(freq, 0);
int currCount = prevCount + offset;
if (currCount == 0) {
freqToCountMap.remove(freq);
} else {
freqToCountMap.put(freq, currCount);
}
}
public void deleteOne(int number) {
int prevFreq = numToFreqMap.getOrDefault(number, 0);
int currFreq = prevFreq - 1;
if (prevFreq == 0) {
return;
}
numToFreqMap.put(number, currFreq);
updateFreqCount(prevFreq, -1);
updateFreqCount(currFreq, +1);
}
public boolean hasFrequency(int frequency) {
return freqToCountMap.getOrDefault(frequency, 0) > 0;
}
}
|