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class Solution {
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 public:
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  vector<vector<int>> getSkyline(vector<vector<int>> &buildings) {
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    priority_queue<pair<int, int>> pq;
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    vector<int> co;
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    for (auto b : buildings) {
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      co.push_back(b[0]);
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      co.push_back(b[1]);
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    }
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    sort(co.begin(), co.end());
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    int m = unique(co.begin(), co.end()) - co.begin();
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    int j = 0, preH = 0;
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    vector<vector<int>> ans;
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    for (int i = 0; i < m; i++) {
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      while (j < buildings.size() && buildings[j][0] <= co[i])
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        pq.push(make_pair(buildings[j][2], buildings[j][1])), j++;
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      while (!pq.empty() && pq.top().second <= co[i]) pq.pop();
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      int nowH = pq.empty() ? 0 : pq.top().first;
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      if (nowH != preH) {
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        ans.push_back({co[i], nowH});
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        preH = nowH;
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      }
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    }
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    return ans;
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  }
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};