1741_sort_array_by_increasing_frequency.cpp

#include <vector>
#include <unordered_map>
#include <algorithm>

class Solution {
public:
    std::vector<int> frequencySort(std::vector<int>& nums) {
        std::unordered_map<int, int> freq;
        for (int num : nums) {
            freq[num]++;
        }

        std::sort(nums.begin(), nums.end(), [&freq](int a, int b) {
            if (freq[a] == freq[b]) {
                return a > b;
            }
            return freq[a] < freq[b];
        });

        return nums;
    }
};