panlindrome number; excel column number of excel

Author: jackzhenguo

Math/Math.Lib/ExcelColumnNumberSln.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Math.Lib
+{
+    public class ExcelColumnNumberSln
+    {
+        public int TitleToNumber(string s)
+        {
+            char[] chs= {'A','B','C','D','E','F','G','H','I','J','K',
+            'L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};   
+            Dictionary<char,int> dict = new Dictionary<char,int>();
+            for(int i=0; i<chs.Length;i++) dict.Add(chs[i],i+1);
+            int scnt = s.Length, rtnsum=0;
+            for (int i = scnt - 1,j=0; i >= 0; i--,j++)
+              rtnsum += dict[s[i]] * (int)System.Math.Pow(26, j);
+            return rtnsum;
+        }
+    }
+}

Math/Math.Lib/ExlColumnTitleSln.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Math.Lib
+{
+    //    Given a positive integer, return its corresponding column title as appear in an Excel sheet.
+
+    //For example:
+
+    //    1 -> A
+    //    2 -> B
+    //    3 -> C
+    //    ...
+    //    26 -> Z
+    //    27 -> AA
+    //    28 -> AB 
+    public class ExlColumnTitleSln
+    {
+        public string ConvertToTitle(int n)
+        {
+            //A~Z:26
+            //AA~ZZ:26*26
+            //...
+            if (n == 0) return "A";
+            char[] chdict = new char[]{'A','B','C','D','E','F','G','H','I','J','K',
+            'L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
+            StringBuilder sb = new StringBuilder();
+            while (n > 0)
+            {
+                if (n % 26 == 0)
+                    sb.Append('Z'); 
+                else sb.Append(chdict[n % 26 - 1]);
+                n = n / 26;
+            }
+            IEnumerable<char> rtnchars = sb.ToString().Reverse();
+            sb.Clear();
+            foreach (var ch in rtnchars)
+                sb.Append(ch);
+            return sb.ToString();
+        }
+    }
+}

Math/Math.Lib/IssPalindromeSln.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Math.Lib
+{
+    public class IssPalindromeSln
+    {
+        public bool IsPalindrome(int x)
+        {
+            int palindromex = 0, tmp = x;
+            int sumbit = 0;
+            //calcuate bit count
+            while (tmp > 0)
+            {
+                sumbit++;
+                tmp /= 10;
+            }
+            tmp = x;
+            //get a number reversely
+            while (tmp > 0)
+            {
+                //if palindromex happens overflow, it would return false;
+                palindromex += tmp % 10 * (int)System.Math.Pow(10, --sumbit);               
+                tmp /= 10;
+            }
+            return palindromex == x;
+        }
+    }
+}

Math/Math.Lib/Math.Lib.csproj

@@ -41,15 +41,18 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="AddStringsSln.cs" />
+    <Compile Include="ExcelColumnNumberSln.cs" />
+    <Compile Include="ExlColumnTitleSln.cs" />
     <Compile Include="HappyNumber.cs" />
+    <Compile Include="IssPalindromeSln.cs" />
     <Compile Include="MinimumMovesSln.cs" />
     <Compile Include="MissingNumberSln.cs" />
     <Compile Include="Nthdigit.cs" />
     <Compile Include="PerfectNumberSln.cs" />
     <Compile Include="PowerOfTwoSln.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="ReverseIntegarSln - Copy.cs" />
     <Compile Include="ReverseIntegarSln.cs" />
+    <Compile Include="Sqrtx.cs" />
   </ItemGroup>
   <ItemGroup>
     <Content Include="Floyd%27sTortoiseandHare.jpg" />