Maximum Building Height LeetCode solution in C++

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class Solution {
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 public:
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  int maxBuilding(int n, vector<vector<int>> &restrictions) {
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    restrictions.push_back({1, 0});
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    restrictions.push_back({n, n - 1});
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    sort(restrictions.begin(), restrictions.end());
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    for (int i = restrictions.size() - 2; i >= 0; --i) {
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      restrictions[i][1] = min(
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          restrictions[i][1], restrictions[i + 1][1] + restrictions[i + 1][0] - restrictions[i][0]);
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    }
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    int ans = 0;
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    for (int i = 1; i < restrictions.size(); ++i) {
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      restrictions[i][1] = min(
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          restrictions[i][1], restrictions[i - 1][1] + restrictions[i][0] - restrictions[i - 1][0]);
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      ans = max(ans, (restrictions[i - 1][1] + restrictions[i][0] - restrictions[i - 1][0] +
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                      restrictions[i][1]) /
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                         2);
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    }
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    return ans;
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  }
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};