Leetcode 931 Solution

This article provides solution to leetcode question 931 (maximum-frequency-stack)
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https://leetcode.com/problems/maximum-frequency-stack

Solution

class FreqStack {
    int maxFreq;
    unordered_map<int, vector<int>> values;
    unordered_map<int, int> freq;
public:
    FreqStack() {
        maxFreq = 0;
    }

    void push(int val) {
        freq[val] += 1;
        values[freq[val]].push_back(val);

        maxFreq = max(maxFreq, freq[val]);
    }

    int pop() {
        int res = values[maxFreq].back();

        values[maxFreq].pop_back();
        if (values[maxFreq].empty())
        {
            values.erase(maxFreq);
            maxFreq--;
        }
        freq[res]--;

        return res;
    }
};

/**
 * Your FreqStack object will be instantiated and called as such:
 * FreqStack* obj = new FreqStack();
 * obj->push(val);
 * int param_2 = obj->pop();
 */