Create maximum-average-pass-ratio.cpp

Author: kamyu104

C++/maximum-average-pass-ratio.cpp

@@ -0,0 +1,27 @@
+// Time:  O(n + mlogn)
+// Space: O(n)
+
+class Solution {
+public:
+    double maxAverageRatio(vector<vector<int>>& classes, int extraStudents) {
+        static const auto& profit = [](double a, double b) {
+            return (a + 1) / (b + 1) - a / b;
+        };
+
+        vector<tuple<double, int, int>> max_heap;
+        for (const auto& c : classes) {
+            max_heap.emplace_back(profit(c[0], c[1]), c[0], c[1]);
+        }
+        make_heap(begin(max_heap), end(max_heap));
+        for (; extraStudents > 0; --extraStudents) {
+            auto [_, a, b] = max_heap.front();
+            ++a, ++b;
+            pop_heap(begin(max_heap), end(max_heap)); max_heap.pop_back();
+            max_heap.emplace_back(profit(a, b), a, b); push_heap(begin(max_heap), end(max_heap));
+        }
+        return accumulate(cbegin(max_heap), cend(max_heap), 0.0,
+                          [](const auto& total, const auto& x) {
+                              return total + float(get<1>(x)) / get<2>(x);
+                          }) / size(classes);
+    }
+};