Insert Delete GetRandom O(1) LeetCode solution in C++

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class RandomizedSet {
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 public:
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  unordered_map<int, int> mp;
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  vector<int> v;
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  RandomizedSet() {}
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  bool insert(int val) {
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    if (mp.find(val) != mp.end()) return false;
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    mp[val] = v.size();
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    v.push_back(val);
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    return true;
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  }
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  bool remove(int val) {
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    if (mp.find(val) != mp.end()) {
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      v[mp[val]] = v.back();
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      mp[v.back()] = mp[val];
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      v.pop_back();
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      mp.erase(val);
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      return true;
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    }
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    return false;
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  }
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  int getRandom() {
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    return v[rand() % v.size()];
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  }
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};