Cheapest Flights Within K Stops LeetCode solution in C++

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class Solution {
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 public:
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#define f first
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#define s second
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  int findCheapestPrice(int n, vector<vector<int>> &flights, int src, int dst, int k) {
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    priority_queue<array<int, 3>, vector<array<int, 3>>, greater<array<int, 3>>> pq;
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    unordered_map<int, vector<pair<int, int>>> g;
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    for (auto &f : flights) {
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      g[f[0]].push_back({f[1], f[2]});
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    }
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    vector<int> dis(n, INT_MAX);
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    pq.push({0, src, 0});
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    while (!pq.empty()) {
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      int c = pq.top()[0];
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      int cur = pq.top()[1];
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      int lvl = pq.top()[2];
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      pq.pop();
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      if (cur == dst) return c;
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      if (lvl > k || lvl >= dis[cur]) continue;
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      dis[cur] = lvl;
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      for (auto &nei : g[cur]) {
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        pq.push({c + nei.s, nei.f, lvl + 1});
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      }
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    }
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    return -1;
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  }
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};