快速排序和选择模版类

template<typename T>
void insert_sort(T *array,int start,int end)
{for (int i = start + 1; i < end + 1; ++i) {int j = i - 1 ;T key = array[i];while (j >= start &&  key < array[j]){array[j+1] = array[j];j--;}array[j+1] = key;}
}
template <typename T>
KeyValuePair partition(T *array,int start,int end ,const T key)
{KeyValuePair line(start-1,start-1);for (int i = start; i < end + 1; ++i) {if(array[i] < key){line.key++;line.value++;T temp = array[i];array[i] = array[line.value];array[line.value] = array[line.key];array[line.key] = temp;}else if(array[i] == key){line.value++;array[i] = array[line.value];array[line.value] = key;}}return line;
}
template<typename T>
T select(T*array,int start,int end,int index)
{if(start == end) return array[start];const int constant_num = 5;int remainder = (end - start + 1) % constant_num;int zero = remainder == 0 ? 0 : 1;int num = (end - start + 1) / constant_num + zero;T *median = new T[num];if(remainder){insert_sort<T>(array,start + (num - 1 ) * constant_num,start + (num - 1 ) * constant_num + remainder-1);median[num-1] = array[start + (num - 1 ) * constant_num + (remainder - 1)/2];}for (int i = 0; i < num - zero; ++i) {insert_sort<T>(array,start + i * constant_num,start + (i+1) * constant_num - 1);median[i] = array[start + i * constant_num + constant_num / 2];}T key = select<T>(median,0,num-1,num/2 + (num % 2 == 0 ? 0 : 1));delete[] median;//划分int middle = partition<T>(array,start,end,key).value;//递归求解int position = middle - start + 1;if(index == position){return  array[middle];}else if(index < position){return select<T>(array,start,middle-1,index);}else{return select<T>(array,middle + 1,end,index - position);}
}
template<typename T>
void quick_sort(T *array,int start,int end)
{if(start<end){T median = select<T>(array,start,end,(end - start + 1)/2 + (end - start + 1)%2);KeyValuePair middle_line = partition<T>(array,start,end,median);quick_sort<T>(array,start,middle_line.key);quick_sort<T>(array,middle_line.value + 1,end);}
}