49 归并排序和快速排序

原文：https://www.cnblogs.com/wanmeishenghuo/p/9688158.html 参考狄泰软件相关教程

 

 

 

 

 

归并示意图：

 

 

程序入下：

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#ifndef SORT_H #define SORT_H   #include "Object.h"   namespace DTLib {   class Sort : public Object { private:     Sort();     Sort(const Sort&);     Sort& operator = (const Sort&);       template <typename T>     static void Swap(T& a, T& b)     {         T c(a);         a = b;         b = c;     }       template < typename T >     static void Merge(T src[], T helper[], int begin, int mid, int end, bool min2max=true)     {         int i = begin;         int j = mid + 1;         int k = begin;  //代表辅助空间起始位置           while( (i <= mid) && (j <= end) )         {             if( min2max ? (src[i] < src[j]) : (src[i] > src[j]) )             {                 helper[k++] = src[i++];             }             else             {                 helper[k++] = src[j++];             }         }           while( i <= mid)         {             helper[k++] = src[i++];         }           while( j <= end )         {             helper[k++] = src[j++];         }           for(i = begin; i <= end; i++)         {             src[i] = helper[i];         }     }       template < typename T >     static void Merge(T src[], T helper[], int begin, int end, bool min2max=true)     {         if( begin < end )         {             int mid = (begin + end) / 2;               Merge(src, helper, begin, mid, min2max);             Merge(src, helper, mid+1, end, min2max);               Merge(src, helper, begin, mid, end, min2max); //真正的归并操作         }     }   public:     template < typename T >     static void Select(T array[], int len, bool min2max=true)     {         for(int i = 0; i < len; i++)         {             int min = i;             for(int j = i + 1; j < len; j++)             {                 if( min2max ? (array[min] > array[j]) : (array[min] < array[j]) )                 {                     min = j;                 }             }               if( min != i)             {                 Swap(array[i], array[min]);             }         }     }       template < typename T >     static void Insert(T array[], int len, bool min2max=true)     {         for(int i=1; i < len; i++)  //从1开始，第0个元素没有必要插入操作         {             int k = i;             T e = array[i];               for(int j=i-1; (j>=0) && (min2max ? (array[j] > e) : (array[j] < e)); j--)             {                 array[j+1] = array[j];                 k = j;             }               if( k != i )   //赋值比“比较操作耗时”             {                 array[k] = e;             }         }     }       template < typename T >     static void Bubble(T array[], int len, bool min2max=true)     {         bool exchange = true;           for(int i=0; (i<len) && exchange; i++)         {             exchange = false;               for(int j=len-1; j>i; j--)             {                 if(min2max ? (array[j] < array[j-1]) : (array[j] > array[j-1]))                 {                     Swap(array[j], array[j-1]);                     exchange = true;                 }             }         }     }       template < typename T >     static void Shell(T array[], int len, bool min2max=true)     {         int d = len;         do         {             d = d / 3 + 1; //d的减小方式（实践证明这样做效果比较好）               for(int i = d; i < len; i+=d)             {                 int k = i;                 T e = array[i];                   for(int j=i-d; (j>=0) && (min2max ? (array[j] > e) : (array[j] < e)); j-=d)                 {                     array[j+d] = array[j];                     k = j;                 }                   if( k != i )   //赋值比“比较操作耗时”                 {                     array[k] = e;                 }             }           }while( d > 1 );     }       template < typename T >     static void Merge(T array[], int len, bool min2max=true)     {         T* helper = new T[len];           if( helper != NULL )         {             Merge(array, helper, 0, len - 1, min2max);         }           delete[] helper;     } };   }   #endif // SORT_H

　

注意：归并排序是一种稳定的排序算法

 

 

 

 

图解：

 

 

代码如下：

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#ifndef SORT_H #define SORT_H   #include "Object.h"   namespace DTLib {   class Sort : public Object { private:     Sort();     Sort(const Sort&);     Sort& operator = (const Sort&);       template <typename T>     static void Swap(T& a, T& b)     {         T c(a);         a = b;         b = c;     }       template < typename T >     static void Merge(T src[], T helper[], int begin, int mid, int end, bool min2max=true)     {         int i = begin;         int j = mid + 1;         int k = begin;  //代表辅助空间起始位置           while( (i <= mid) && (j <= end) )         {             if( min2max ? (src[i] < src[j]) : (src[i] > src[j]) )             {                 helper[k++] = src[i++];             }             else             {                 helper[k++] = src[j++];             }         }           while( i <= mid)         {             helper[k++] = src[i++];         }           while( j <= end )         {             helper[k++] = src[j++];         }           for(i = begin; i <= end; i++)         {             src[i] = helper[i];         }     }       template < typename T >     static void Merge(T src[], T helper[], int begin, int end, bool min2max)     {         if( begin < end )         {             int mid = (begin + end) / 2;               Merge(src, helper, begin, mid, min2max);             Merge(src, helper, mid+1, end, min2max);               Merge(src, helper, begin, mid, end, min2max); //真正的归并操作         }     }       template < typename T >     static int Partition(T array[], int begin, int end, bool min2max)     {         T pv = array[begin];           while( begin < end )         {             while( (begin < end) && (min2max ? (array[end] > pv) : (array[end] < pv)) )             {                 end--;             }               Swap(array[begin], array[end]);               while( (begin < end) && (min2max ? (array[begin] <= pv) : (array[begin] >= pv)) )             {                 begin++;             }               Swap(array[begin], array[end]);         }           array[begin] = pv;  //基准就位           return begin;     }       template < typename T >     static void Quick(T array[], int begin, int end, bool min2max)     {         if( begin < end )         {             int pivot = Partition(array, begin, end, min2max);               Quick(array, begin, pivot - 1, min2max);             Quick(array, pivot + 1, end, min2max);         }     }   public:     template < typename T >     static void Select(T array[], int len, bool min2max=true)     {         for(int i = 0; i < len; i++)         {             int min = i;             for(int j = i + 1; j < len; j++)             {                 if( min2max ? (array[min] > array[j]) : (array[min] < array[j]) )                 {                     min = j;                 }             }               if( min != i)             {                 Swap(array[i], array[min]);             }         }     }       template < typename T >     static void Insert(T array[], int len, bool min2max=true)     {         for(int i=1; i < len; i++)  //从1开始，第0个元素没有必要插入操作         {             int k = i;             T e = array[i];               for(int j=i-1; (j>=0) && (min2max ? (array[j] > e) : (array[j] < e)); j--)             {                 array[j+1] = array[j];                 k = j;             }               if( k != i )   //赋值比“比较操作耗时”             {                 array[k] = e;             }         }     }       template < typename T >     static void Bubble(T array[], int len, bool min2max=true)     {         bool exchange = true;           for(int i=0; (i<len) && exchange; i++)         {             exchange = false;               for(int j=len-1; j>i; j--)             {                 if(min2max ? (array[j] < array[j-1]) : (array[j] > array[j-1]))                 {                     Swap(array[j], array[j-1]);                     exchange = true;                 }             }         }     }       template < typename T >     static void Shell(T array[], int len, bool min2max=true)     {         int d = len;         do         {             d = d / 3 + 1; //d的减小方式（实践证明这样做效果比较好）               for(int i = d; i < len; i+=d)             {                 int k = i;                 T e = array[i];                   for(int j=i-d; (j>=0) && (min2max ? (array[j] > e) : (array[j] < e)); j-=d)                 {                     array[j+d] = array[j];                     k = j;                 }                   if( k != i )   //赋值比“比较操作耗时”                 {                     array[k] = e;                 }             }           }while( d > 1 );     }       template < typename T >     static void Merge(T array[], int len, bool min2max=true)     {         T* helper = new T[len];           if( helper != NULL )         {             Merge(array, helper, 0, len - 1, min2max);         }           delete[] helper;     }       template < typename T >     static void Quick(T array[], int len, bool min2max=true)     {         Quick(array, 0, len - 1, min2max);     } };   }   #endif // SORT_H

　　

注意：快速排序是一种不稳定的排序算法

 

小结：