feat : add C# solution

202508/2438 ProductQueries/C#/2438 ProductQueries.sln

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+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.5.2.0
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ProductQueries", "C#\ProductQueries.csproj", "{412F89C4-B1BF-D819-298B-9C873A098742}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{412F89C4-B1BF-D819-298B-9C873A098742}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{412F89C4-B1BF-D819-298B-9C873A098742}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{412F89C4-B1BF-D819-298B-9C873A098742}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{412F89C4-B1BF-D819-298B-9C873A098742}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {BDF3A5A3-29B8-4169-8A46-A13A7DE900D8}
+	EndGlobalSection
+EndGlobal

202508/2438 ProductQueries/C#/ProductQueries.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

202508/2438 ProductQueries/C#/Program.cs

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+using System;
+
+public class Solution
+{
+    public int[] ProductQueries(int n, int[][] queries)
+    {
+        // 1. n => calculate in powers of 2
+        // 2. get number array without 0
+        var powers = CalPower(n);
+
+        return CalQueries(powers, queries);
+
+    }
+
+    private int[] CalPower(int n)
+    {
+        var result = new List<int>();
+
+        while (n > 0)
+        {
+            var num = n % 2;
+            result.Add(num);
+            n /= 2;
+        }
+
+        var newResult = new List<int>();
+        for (var i = 0; i < result.Count; i++)
+        {
+            if (result[i] != 0)
+            {
+                var ans = (int)Math.Pow(2, i);
+                newResult.Add(ans);
+            }
+        }
+        return newResult.ToArray();
+    }
+
+    private int[] CalQueries(int[] powers, int[][] queries)
+    {
+        const int MOD = 1000000007;
+        var result = new List<int>();
+
+        foreach (var query in queries)
+        {
+            long count = 1;
+            for (var i = query[0]; i <= query[1]; i++)
+            {
+                count = (count * powers[i]) % MOD;
+            }
+            result.Add(count);
+        }
+
+        return result.ToArray();
+    }
+}
+
+class Program
+{
+    static void Main()
+    {
+        var Solution = new Solution();
+
+        var ans = Solution.ProductQueries(15, [[0, 1], [2, 2], [0, 3]]);
+        Console.WriteLine(string.Join(", ", ans));
+
+        ans = Solution.ProductQueries(919, [[5,5],[4,4],[0,1],[1,5],[4,6],[6,6],[5,6],[0,3],[5,5],[5,6],[1,2],[3,5],[3,6],[5,5],[4,4],[1,1],[2,4],[4,5],[4,4],[5,6],[0,4],[3,3],[0,4],[0,5],[4,4],[5,5],[4,6],[4,5],[0,4],[6,6],[6,6],[6,6],[2,2],[0,5],[1,4],[0,3],[2,4],[5,5],[6,6],[2,2],[2,3],[5,5],[0,6],[3,3],[6,6],[4,4],[0,0],[0,2],[6,6],[6,6],[3,6],[0,4],[6,6],[2,2],[4,6]]);
+         Console.WriteLine(string.Join(", ", ans));
+    }
+}

202508/2438 ProductQueries/description.md

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+Given a positive integer n, there exists a 0-indexed array called powers, composed of the minimum number of powers of 2 that sum to n. The array is sorted in non-decreasing order, and there is only one way to form the array.
+
+You are also given a 0-indexed 2D integer array queries, where queries[i] = [lefti, righti]. Each queries[i] represents a query where you have to find the product of all powers[j] with lefti <= j <= righti.
+
+Return an array answers, equal in length to queries, where answers[i] is the answer to the ith query. Since the answer to the ith query may be too large, each answers[i] should be returned modulo 109 + 7.