add Ch8 Q1, show elapsed time

.vscode/launch.json

@@ -0,0 +1,24 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": ".NET Core Launch (console)",
+            "type": "coreclr",
+            "request": "launch",
+            "preLaunchTask": "build",
+            "program": "${workspaceFolder}/ctci/bin/Debug/netcoreapp1.1/ctci.dll",
+            "args": [],
+            "cwd": "${workspaceFolder}/ctci",
+            "console": "integratedTerminal",
+            "stopAtEntry": false
+        },
+        {
+            "name": ".NET Core Attach",
+            "type": "coreclr",
+            "request": "attach"
+        }
+    ]
+}

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "dotnet.defaultSolution": "ctci.sln"
+}

.vscode/tasks.json

@@ -0,0 +1,41 @@
+{
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "build",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "build",
+                "${workspaceFolder}/ctci.sln",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "publish",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "publish",
+                "${workspaceFolder}/ctci.sln",
+                "/property:GenerateFullPaths=true",
+                "/consoleloggerparameters:NoSummary"
+            ],
+            "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "watch",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "watch",
+                "run",
+                "--project",
+                "${workspaceFolder}/ctci.sln"
+            ],
+            "problemMatcher": "$msCompile"
+        }
+    ]
+}

Ch 01. Arrays and Strings/Q1_07_Rotate_Matrix.cs

@@ -31,10 +31,10 @@ private void Rotate(int[][] matrix)
         {
             if (!IsSquareMatrix(matrix))  // Edge case + error checking.
             {
-                return false;
+                return;
             }
-            
-            int matrixSize = matrix.Length
+
+            int matrixSize = matrix.Length;
             for (int layer = 0; layer < matrixSize / 2; layer++)
             {
                 int startIndex = layer;
@@ -71,7 +71,7 @@ public override void Run()
 
             AssortedMethods.PrintMatrix(matrix);
 
-            Rotate(matrix, size);
+            Rotate(matrix);
             Console.WriteLine();
             AssortedMethods.PrintMatrix(matrix);
         }

Ch 08. Recursion and Dynamic Programming/Ch 08. Recursion and Dynamic Programming.csproj

@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <ItemGroup>
+    <ProjectReference Include="..\ctci.Contracts\ctci.Contracts.csproj" />
+    <ProjectReference Include="..\ctci.Library\ctci.Library.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp1.1</TargetFramework>
+    <RootNamespace>Chapter08</RootNamespace>
+    <!-- <ImplicitUsings></ImplicitUsings>
+    <Nullable>enable</Nullable> -->
+  </PropertyGroup>
+
+</Project>

Ch 08. Recursion and Dynamic Programming/Q8_01_Triple_Step.cs

@@ -0,0 +1,69 @@
+using ctci.Contracts;
+using ctci.Library;
+using System;
+
+namespace Chapter08
+{
+    public class Q8_01_Triple_Step : Question
+    {
+        public class QuestionA
+        {
+            public static int CountWays(int n)
+            {
+                if (n < 0)
+                {
+                    return 0;
+                }
+                else if (n == 0)
+                {
+                    return 1;
+                }
+                else
+                {
+                    return CountWays(n - 1) + CountWays(n - 2) + CountWays(n - 3);
+                }
+            }
+        }
+
+        public class QuestionB
+        {
+            public static int CountWays(int n)
+            {
+                int[] map = new int[n + 1];
+                AssortedMethods.FillArray<int>(map, -1);
+                return CountWays(n, map);
+            }
+
+            public static int CountWays(int n, int[] memo)
+            {
+                if (n < 0)
+                {
+                    return 0;
+                }
+                else if (n == 0)
+                {
+                    return 1;
+                }
+                else if (memo[n] > -1)
+                {
+                    return memo[n];
+                }
+                else
+                {
+                    memo[n] = CountWays(n - 1, memo) + CountWays(n - 2, memo) + CountWays(n - 3, memo);
+                    return memo[n];
+                }
+            }
+        }
+
+        public override void Run()
+        {
+            for (int i = 0; i < 30; i++)
+            {
+                int c1 = QuestionB.CountWays(i);
+                int c2 = QuestionA.CountWays(i);
+               Console.WriteLine($"{i}: {c1} {c2}");
+            }
+        }
+    }
+}

ctci.Library/AssortedMethods.cs

@@ -2306,5 +2306,13 @@ public static string[] GetListOfWords()
             };
             return wordList;
         }
+
+        public static void FillArray<T>(T[] arr, T val)
+        {
+            for (int i = 0; i < arr.Length; i++)
+            {
+                arr[i] = val;
+            }
+        }
     }
 }

ctci.sln

@@ -27,6 +27,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Ch 16. Moderate", "Ch 16. M
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Ch 04. Trees", "Ch 04. Trees\Ch 04. Trees.csproj", "{AF583937-1A80-407F-B683-3FEED7F3BC16}"
 EndProject
+Project("{8E563D72-A200-4BB7-8AB8-A93BEED3A5B7}") = "Ch 08. Recursion and Dynamic Programming", "Ch 08. Recursion and Dynamic Programming\Ch 08. Recursion and Dynamic Programming.csproj", "{CF860E19-E678-4DB8-BF4A-87A92B58F7E7}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -73,6 +75,10 @@ Global
 		{AF583937-1A80-407F-B683-3FEED7F3BC16}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{AF583937-1A80-407F-B683-3FEED7F3BC16}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{AF583937-1A80-407F-B683-3FEED7F3BC16}.Release|Any CPU.Build.0 = Release|Any CPU
+		{CF860E19-E678-4DB8-BF4A-87A92B58F7E7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{CF860E19-E678-4DB8-BF4A-87A92B58F7E7}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{CF860E19-E678-4DB8-BF4A-87A92B58F7E7}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{CF860E19-E678-4DB8-BF4A-87A92B58F7E7}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -88,5 +94,6 @@ Global
 		{90D56A57-CEAD-42F8-A978-BC2D33530E0E} = {8E563D72-A200-4BB7-8AB8-A93BEED3A5B7}
 		{AE0D044B-1AE9-430F-B05D-ADAC72C407B8} = {8E563D72-A200-4BB7-8AB8-A93BEED3A5B7}
 		{AF583937-1A80-407F-B683-3FEED7F3BC16} = {8E563D72-A200-4BB7-8AB8-A93BEED3A5B7}
+		{CF860E19-E678-4DB8-BF4A-87A92B58F7E7} = {8E563D72-A200-4BB7-8AB8-A93BEED3A5B7}
 	EndGlobalSection
 EndGlobal

ctci/Program.cs

@@ -1,12 +1,14 @@
 using Chapter01;
 using Chapter02;
-using Chapter04;
+//using Chapter04;
 using Chapter05;
+using Chapter08;
 using Chapter10;
 using Chapter16;
 using ctci.Contracts;
 using Introduction;
 using System;
+using System.Diagnostics;
 
 namespace ctci
 {
@@ -28,7 +30,7 @@ private static void Main(string[] args)
                     new Q1_04_Palindrome_Permutation(),
                     new Q1_05_One_Away_A(),
                     new Q1_06_String_Compression(),
-                    new Q1_07_Rotate_Matrix(),
+                    // new Q1_07_Rotate_Matrix(),
                     new Q1_08_Zero_Matrix(),
                     new Q1_09_String_Rotation(),
                 },
@@ -44,17 +46,17 @@ private static void Main(string[] args)
                     new Q2_08_Loop_Detection()
                 },
 
-                new Question[] {
-                    new Q4_02_CreateMinimalBSTfromSortedUniqueArray(),
-                    new Q4_03_List_of_Depths(),
-                    new Q4_04_CheckBalanced(),
-                    new Q4_05_Validate_BST(),
-                    new Q4_06_Successor(),
-                    new Q4_08_LowestCommonAncestorNotBST(),
-                    new Q4_09_BST_Sequence(),
-                    new Q4_10_Check_SubTree(),
-                    new ReplaceNodeInImmutableTree()
-                },
+                // new Question[] {
+                //     new Q4_02_CreateMinimalBSTfromSortedUniqueArray(),
+                //     new Q4_03_List_of_Depths(),
+                //     new Q4_04_CheckBalanced(),
+                //     new Q4_05_Validate_BST(),
+                //     new Q4_06_Successor(),
+                //     new Q4_08_LowestCommonAncestorNotBST(),
+                //     new Q4_09_BST_Sequence(),
+                //     new Q4_10_Check_SubTree(),
+                //     new ReplaceNodeInImmutableTree()
+                // },
 
                 new Question[] {
                     new Q5_01_Insertion(),
@@ -66,6 +68,10 @@ private static void Main(string[] args)
                     new Q5_08_Draw_Line()
                 },
 
+                new Question[] {
+                    new Q8_01_Triple_Step()
+                },
+
                 new Question[] {
                     new Q10_01_Sorted_Merge(),
                     new Q10_02_Group_Anagrams(),
@@ -92,13 +98,19 @@ private static void Main(string[] args)
 
             foreach (var chapter in chapters)
             {
+                Stopwatch stopwatch = new Stopwatch();
                 foreach (Question q in chapter)
                 {
                     Console.WriteLine("\n\n");
                     Console.WriteLine($"// Executing: {q.Name}");
                     Console.WriteLine("// ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----");
 
+                    stopwatch.Start();
                     q.Run();
+                    stopwatch.Stop();
+
+                    Console.WriteLine();
+                    Console.WriteLine($"// Elapsed: {stopwatch.Elapsed}");
                 }
             }
 

ctci/ctci.csproj

@@ -17,6 +17,7 @@
     <ProjectReference Include="..\Ch 10. Sorting and Searching\Ch 10. Sorting and Searching.csproj" />
     <ProjectReference Include="..\Ch 16. Moderate\Ch 16. Moderate.csproj" />
     <ProjectReference Include="..\Introduction\Introduction.csproj" />
+    <ProjectReference Include="..\Ch 08. Recursion and Dynamic Programming\Ch 08. Recursion and Dynamic Programming.csproj" />
   </ItemGroup>
 
 </Project>