排序算法之归并排序(模板类)

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#include<algorithm>using namespace std;template <class T>class element{public:element() { key = T(0);}~element() {};public:T key;};#pragma onceclass merge_sort{public:merge_sort(void);~merge_sort(void);// 排序算法template <class T>void Sort(element<T> list[], int n);// 归并template <class T>void Merge(element<T> list[], element<T> sorted[], int i, int m, int n);template <class T>void merge_pass(element<T> list[], element<T> sorted[], int n, int length);};template <class T>void merge_sort::Sort(element<T> list[], int n){int length = 1;element<T> *extra = new element<T>[2*n];while(length < n){merge_pass(list, extra, n , length);length *= 2;merge_pass(extra, list, n, length);length *= 2;}delete[]extra;}// 归并两个已经排序的表// 将list[i],...,list[m] 和list[m+1],...,list[n]两个有序表归并为一个有序表(sorted[i],...,sorted[n])template <class T>void merge_sort::Merge(element<T> list[], element<T>  sorted[], int i, int m, int n){// merge two sorted list files: list[i],...,list[m], \// and obtain a sorted list: sorted[i],...,sorted[n]int j,k,t;j = m+1; // index for the second sublistk = i;while(i <= m && j <=n ){if(list[i].key <= list[j].key){sorted[k++] = list[i++];}else{sorted[k++] = list[j++];}}if(i > m){for(t = j; t <= n; t++){sorted[k+t-j] = list[t];}}else{for(t = i; t <= m; t++){sorted[k+t-i] = list[t];}}}template <class T>void merge_sort::merge_pass(element<T> list[], element<T> sorted[], int n, int length){int i = 0, j = 0;for(i = 0; i <= n-2*length; i += 2*length){Merge(list, sorted, i, i+length-1, i+2*length-1);}if( i+length < n){Merge(list, sorted, i, i+length-1, i+2*length-1);}else{for(j=i; j < n; j++){sorted[j] = list[j];}}}
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