标签：gif include http int iostream using cout pen 递归调用
采用分治的思想 以O(NlogN)最坏的情形运行时间运行
如果对merge的每个递归调用都采用局部声明一个临时数组，那么在任一时刻就可能有logN个临时数组处在活动期
代码如下：
1 #include <iostream>
2 #include <vector>
3 using namespace std;
4 template <typename Comparable>
5 void mergeSort(vector<Comparable> & a)
6 {
7 vector<Comparable> tmpArray(a.size());
8 mergeSort(a,tmpArray,0,a.size()-1);
9 }
10 template <typename Comparable>
11 void mergeSort(vector<Comparable> & a,vector<Comparable> & tmpArray,int left,int right)
12 {
13 if(left<right)
14 {
15 int center = (left+right)/2;
16 mergeSort(a,tmpArray,left,center);
17 mergeSort(a,tmpArray,center+1,right);
18 merge(a,tmpArray,left,center+1,right);
19 }
20 }
21 template <typename Comparable>
22 void merge(vector<Comparable> & a,vector<Comparable> & tmpArray,int leftPos,int rightPos,int rightEnd)
23 {
24 int leftEnd = rightPos-1;
25 int tmpPos = leftPos;
26 int numElements = rightEnd - leftPos + 1;
27
28 while(leftPos <= leftEnd && rightPos <= rightEnd)
29 if(a[leftPos] <= a[rightPos])
30 tmpArray[tmpPos++] = a[leftPos++];
31 else
32 tmpArray[tmpPos++] = a[rightPos++];
33
34 while(leftPos <= leftEnd)
35 tmpArray[tmpPos++] = a[leftPos++];
36 while(rightPos <= rightEnd)
37 tmpArray[tmpPos++] = a[rightPos++];
38
39 for(int i=0;i<numElements;i++,rightEnd--)
40 a[rightEnd] = tmpArray[rightEnd];
41 }
42 int main()
43 {
44 vector<int> ivec;
45 ivec.push_back(1);
46 ivec.push_back(9);
47 ivec.push_back(2);
48 ivec.push_back(10);
49 ivec.push_back(3);
50 ivec.push_back(11);
51 ivec.push_back(4);
52 ivec.push_back(12);
53 ivec.push_back(5);
54 ivec.push_back(13);
55 ivec.push_back(6);
56 ivec.push_back(14);
57 ivec.push_back(7);
58 ivec.push_back(15);
59 ivec.push_back(8);
60 ivec.push_back(16);
61 mergeSort(ivec);
62 for(int j = 0;j<ivec.size();j++)
63 cout<<ivec[j]<<endl;
64 return 0;
65 }
运行结果：
标签：gif include http int iostream using cout pen 递归调用
原文地址：http://www.cnblogs.com/luozhijun/p/6880429.html
