problems/1792-maximum-average-pass-ratio/csharp/Program.cs

@@ -6,7 +6,45 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
-public class Solution {
+public class Solution
+{
+    public double MaxAverageRatio(int[][] classes, int extraStudents)
+    {
+        // use priority queue
+        var pq = new PriorityQueue<ClassInfo, double>();
+
+        // 初始化：將所有班級加入優先佇列 
+        for (int i = 0; i < classes.Length; i++)
+        {
+            int pass = classes[i][0];
+            int total = classes[i][1];
+
+            double gain = CalculateGain(pass, total);
+
+            pq.Enqueue(new ClassInfo(pass, total), -gain);
+        }
+
+        for (int i = 0; i < extraStudents; i++)
+        {
+            var classInfo = pq.Dequeue();
+
+            classInfo.Pass++;
+            classInfo.Total++;
+
+            double newGain = CalculateGain(classInfo.Pass, classInfo.Total);
+            pq.Enqueue(classInfo, -newGain);
+        }
+
+        double totalRatio = 0;
+        while (pq.Count > 0)
+        {
+            var classInfo = pq.Dequeue();
+            totalRatio += (double)classInfo.Pass / classInfo.Total;
+        }
+
+        return totalRatio / classes.Length;
+    }
+
     public double MaxAverageRatioByBruteForce(int[][] classes, int extraStudents)
     {
         var n = classes.Length;
@@ -54,7 +92,14 @@ public class Solution {
         return CalculateAvergaeRatio(pass, total);
     }
 
-    private double CalculateAvergaeRatio(int[] pass, int[] total) {
+    private double CalculateGain(int pass, int total)
+    {
+        // 計算提升率
+        return (double)(pass + 1) / (total + 1) - (double)pass / total;
+    }
+
+    private double CalculateAvergaeRatio(int[] pass, int[] total)
+    {
         double sum = 0;
         for (var i = 0; i < pass.Length; i++)
         {
@@ -64,6 +109,18 @@ public class Solution {
     }
 }
 
+public class ClassInfo
+{
+    public int Pass { get; set; }
+    public int Total { get; set; }
+
+    public ClassInfo(int pass, int total)
+    {
+        Pass = pass;
+        Total = total;
+    }
+}
+
 // 測試程式
 public class Program
 {
@@ -98,7 +155,7 @@ public class Program
         // Actual: 
         Console.WriteLine("Actual: ");
         Console.WriteLine($"Brute Force: {solution.MaxAverageRatioByBruteForce(classes, extraStudents):F6}");
-        //Console.WriteLine($"output: {solution.MaxAverageRatio(classes, extraStudents):F6}");
+        Console.WriteLine($"Priority Queue: {solution.MaxAverageRatio(classes, extraStudents):F6}");
     }
 
 
@@ -125,6 +182,6 @@ public class Program
         // Actual: 
         Console.WriteLine("Actual: ");
         Console.WriteLine($"Brute Force: {solution.MaxAverageRatioByBruteForce(classes, extraStudents):F6}");
-        //Console.WriteLine($"output: {solution.MaxAverageRatio(classes, extraStudents):F6}");
+        Console.WriteLine($"Priority Queue: {solution.MaxAverageRatio(classes, extraStudents):F6}");
     }
 }