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1224. Maximum Equal Frequency 👍

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class Solution {
 public:
  int maxEqualFreq(vector<int>& nums) {
    int ans = 0;
    int maxFreq = 0;
    unordered_map<int, int> count;
    unordered_map<int, int> freq;

    for (int i = 0; i < nums.size(); ++i) {
      const int num = nums[i];
      --freq[count[num]];
      ++count[num];
      ++freq[count[num]];
      maxFreq = max(maxFreq, count[num]);
      if (maxFreq == 1 || maxFreq * freq[maxFreq] == i ||
          (maxFreq - 1) * (freq[maxFreq - 1] + 1) == i)
        ans = i + 1;
    }

    return ans;
  }
};

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class Solution {
  public int maxEqualFreq(int[] nums) {
    int ans = 0;
    int maxFreq = 0;
    Map<Integer, Integer> count = new HashMap<>();
    Map<Integer, Integer> freq = new HashMap<>();

    for (int i = 0; i < nums.length; ++i) {
      final int currentFreq = count.getOrDefault(nums[i], 0);
      freq.merge(currentFreq, -1, Integer::sum);
      final int updatedFreq = currentFreq + 1;
      count.put(nums[i], updatedFreq);
      freq.merge(updatedFreq, 1, Integer::sum);
      maxFreq = Math.max(maxFreq, updatedFreq);
      if (maxFreq == 1 || maxFreq * freq.get(maxFreq) == i ||
          (maxFreq - 1) * (freq.get(maxFreq - 1) + 1) == i)
        ans = i + 1;
    }

    return ans;
  }
}

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class Solution:
  def maxEqualFreq(self, nums: list[int]) -> int:
    ans = 0
    maxFreq = 0
    count = collections.Counter()
    freq = collections.Counter()

    for i, num in enumerate(nums):
      freq[count[num]] -= 1
      count[num] += 1
      freq[count[num]] += 1
      maxFreq = max(maxFreq, count[num])
      if maxFreq == 1 or maxFreq * freq[maxFreq] == i or (maxFreq - 1) * (
              freq[maxFreq - 1] + 1) == i:
        ans = i + 1

    return ans