Merge Sorted Arrays

• Time : O(nlogk)
• Space : O(k)

using namespace std;

vector<int> mergeSortedArrays(vector<vector<int>> arrays) {
    priority_queue<array<int,3>, vector<array<int,3>>, greater<array<int,3>>> pq;
    vector<int> res;
    for(int i = 0; i < arrays.size(); i++) {
        if(arrays[i].empty()) continue;
        pq.push({arrays[i][0], i, 1});
    }
    while(!pq.empty()) {
        auto [v, id, idx] = pq.top(); pq.pop();
        res.push_back(v);
        if(arrays[id].size() != idx)
            pq.push({arrays[id][idx], id, idx + 1});
    }
    return res;
}