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jackzhenguojackzhenguo
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two pointers tag
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‎TwoPointers/MergeSortedArraySln.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace TwoPointers.Lib
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{
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//Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.
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//Note:
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//You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements initialized in nums1 and nums2 are m and n respectively.
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public class MergeSortedArraySln
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{
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public void Merge(int[] nums1, int m, int[] nums2, int n)
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{
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int i = m - 1; //指向nums1
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int j = n - 1; //指向nums2
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int k = m + n - 1; //指向合并位置
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while (j >= 0)
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{
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if (i >= 0 && nums1[i] > nums2[i])
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nums1[k--] = nums1[i--];
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else nums1[k--] = nums2[j--];
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}
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}
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}
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}

‎TwoPointers/MoveZeroesSln.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace TwoPointers.Lib
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{
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// Given an array nums, write a function to move all 0’s to the end of it while maintaining the relative order of the non-zero elements.
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//For example, given nums = [0, 1, 0, 3, 12], after calling your function, nums should be [1, 3, 12, 0, 0].
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// Note:
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//1. You must do this in-place without making a copy of the array.
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//2. Minimize the total number of operations.
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public class MoveZeroesSln
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{
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public class Solution
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{
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public void MoveZeroes(int[] nums)
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{
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int i, j = 0; //j始终指向非零数
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for (i = 0; i < nums.Length; i++)
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{
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if (nums[i] == 0)
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{
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while (i < nums.Length && nums[i] == 0)
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i++;
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if (i < nums.Length)
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nums[j++] = nums[i];//找到num[i]不为0
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}
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else
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nums[j++] = nums[i];
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}
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//[0,j)为非零数，[j,nums.Length)应全清零。
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for (int k = j; k < nums.Length; k++)
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nums[k] = 0;
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}
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}
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}
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}

‎TwoPointers/ReverseVowelsSln.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace TwoPointers.Lib
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{
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// Write a function that takes a string as input and reverse only the vowels of a string.
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//Example 1:
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//Given s = "hello", return "holle".
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//1
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//1
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//Example 2:
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//Given s = "leetcode", return "leotcede".
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public class ReverseVowelsSln
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{
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public class Solution
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{
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private List<char> vowels = new List<char> { 'a', 'A', 'e', 'E', 'i', 'I', 'o', 'O', 'u', 'U' };
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private char[] chars;
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public string ReverseVowels(string s)
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{
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chars = s.ToCharArray();
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int lo = 0;
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int hi = s.Length - 1;
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while (lo < hi)
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reverseVowels(ref lo, ref hi);
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return new string(chars);
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}
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public void reverseVowels(ref int lo, ref int hi)
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{
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for (int i = lo; i <= hi; i++, lo++)
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{
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if (vowels.Contains(chars[i]))
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break;
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}
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for (int i = hi; i >= lo; i--, hi = i)
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{
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if (vowels.Contains(chars[i]))
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break;
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}
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if (lo < hi)
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{
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if (chars[lo] != chars[hi])//交换字符
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{
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char tmp = chars[lo];
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chars[lo] = chars[hi];
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chars[hi] = tmp;
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}
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++lo;
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--hi;
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}
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}
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}
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}
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}

‎TwoPointers/TwoPointers.Lib.csproj

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<?xml version="1.0" encoding="utf-8"?>
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<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
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<Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
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<PropertyGroup>
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<Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
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<Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
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<ProjectGuid>{FC40770B-F0C2-489D-BAF0-B50F90701B3D}</ProjectGuid>
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<OutputType>Library</OutputType>
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<AppDesignerFolder>Properties</AppDesignerFolder>
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<RootNamespace>TwoPointers.Lib</RootNamespace>
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<AssemblyName>TwoPointers.Lib</AssemblyName>
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<TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
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<FileAlignment>512</FileAlignment>
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</PropertyGroup>
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<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
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<DebugSymbols>true</DebugSymbols>
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<DebugType>full</DebugType>
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<Optimize>false</Optimize>
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<OutputPath>bin\Debug\</OutputPath>
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<DefineConstants>DEBUG;TRACE</DefineConstants>
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<ErrorReport>prompt</ErrorReport>
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<WarningLevel>4</WarningLevel>
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</PropertyGroup>
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<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
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<DebugType>pdbonly</DebugType>
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<Optimize>true</Optimize>
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<OutputPath>bin\Release\</OutputPath>
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<DefineConstants>TRACE</DefineConstants>
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<ErrorReport>prompt</ErrorReport>
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<WarningLevel>4</WarningLevel>
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</PropertyGroup>
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<ItemGroup>
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<Reference Include="System" />
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<Reference Include="System.Core" />
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<Reference Include="System.Xml.Linq" />
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<Reference Include="System.Data.DataSetExtensions" />
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<Reference Include="Microsoft.CSharp" />
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<Reference Include="System.Data" />
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<Reference Include="System.Xml" />
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</ItemGroup>
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<ItemGroup>
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<Compile Include="MergeSortedArraySln.cs" />
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<Compile Include="MoveZeroesSln.cs" />
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<Compile Include="ReverseVowelsSln.cs" />
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<Compile Include="Properties\AssemblyInfo.cs" />
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<Compile Include="ValidPalindromeSln.cs" />
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</ItemGroup>
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<Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
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<!-- To modify your build process, add your task inside one of the targets below and uncomment it.
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Other similar extension points exist, see Microsoft.Common.targets.
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<Target Name="BeforeBuild">
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</Target>
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<Target Name="AfterBuild">
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</Target>
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-->
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</Project>

‎TwoPointers/ValidPalindromeSln.cs

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace TwoPointers.Lib
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{
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// Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
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//For example,
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//"A man, a plan, a canal: Panama" is a palindrome.
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//"race a car" is not a palindrome.
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class ValidPalindromeSln
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{
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public bool IsPalindrome(string s)
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{
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int i, j;
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if (s == string.Empty) return true;
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for (i = 0, j = s.Length - 1; i < s.Length && j > 0; i++, j--)
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{
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while (i < s.Length && !isAlphanumeric(s[i]))
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i++;
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while (i < j && !isAlphanumeric(s[j]))
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j--;
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if (i >= j) //碰头表示成功！
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break;
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if (!isEqual(s[i], s[j]))
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return false;
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}
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return true;
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}
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private bool isAlphanumeric(char c)
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{
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return char.IsLetter(c) || char.IsDigit(c);
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}
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private bool isEqual(char c1, char c2)
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{
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//要做字符和字母的区别对待，数字和字母字符一定不相等。
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if (char.IsDigit(c1) && char.IsLetter(c2))
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return false;
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if (char.IsDigit(c2) && char.IsLetter(c1))
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return false;
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//如果不考虑以上，请参考数字0和字符P的取值。
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if (c1 == c2) return true;
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int c1int = Convert.ToInt32(c1);
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int c2int = Convert.ToInt32(c2);
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return Math.Abs(c1int - c2int) == 32;
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}
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}
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}

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