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1 #ifndef _SORT_H 2 #define _SORT_H 3 4 // goal: quicksort and insertsort 5 // time: 12/2/2014 6 // author: zrss 7 // reference: introduction to algorithms 8 9 class Sort { 10 public: 11 void quickSort(int A[], int p, int r); 12 void insertSort(int A[], int p, int r); 13 14 private: 15 int partition(int A[], int p, int r); // for quickSort 16 }; 17 18 int Sort::partition(int A[], int p, int r) { 19 int x = A[r]; // use A[r] as pivot node 20 21 int i = p - 1; // point to left part 22 23 // divide A array to three part 24 // A[p - i] <= x 25 // A[(i + 1) - j] > x 26 // A[(j + 1) - r) unknown 27 for (int j = p; j < r; ++j) { 28 if (A[j] <= x) { 29 ++i; 30 if (i != j) { // swap A[i] and A[j] 31 int temp = A[i]; 32 A[i] = A[j]; 33 A[j] = temp; 34 } 35 } 36 } 37 38 // exchange A[i + 1] and A[r] 39 A[r] = A[i + 1]; 40 A[i + 1] = x; 41 42 return (i + 1); 43 } 44 45 void Sort::quickSort(int A[], int p, int r) { 46 if (p < r) { 47 int q = partition(A, p, r); 48 quickSort(A, p, q - 1); 49 quickSort(A, q + 1, r); 50 } 51 } 52 53 void Sort::insertSort(int A[], int p, int r) { 54 for (int j = p + 1; j <= r; ++j) { 55 int key = A[j]; 56 int i = j - 1; 57 while (i >= p && A[i] > key) { // move backward 58 A[i + 1] = A[i]; 59 --i; 60 } 61 62 if (i + 1 != j) { // insert A[j] to right position 63 A[i + 1] = key; 64 } 65 } 66 } 67 68 69 #endif
随机产生100,000个int测试数据
1 #include <cstdio> 2 #include <cstdlib> 3 #include "windows.h" 4 #include "sort.h" 5 6 int main(void) { 7 const int length = 100000; 8 int number[length]; 9 10 for (int i = 0; i < length; ++i) { 11 number[i] = rand(); 12 } 13 14 Sort sort; 15 16 DWORD st = GetTickCount(); 17 18 sort.insertSort(number, 0, length - 1); 19 //sort.quickSort(number, 0, length - 1); 20 21 DWORD ed = GetTickCount(); 22 23 printf("InsertSort use time: %dms\n", ed - st); 24 //printf("QuickSort use time: %dms\n", ed - st); 25 26 system("pause"); 27 return 0; 28 }
InsertSort use time: 2200ms
QuickSort use time: 0ms
System: Windows 7 professional Service Pack 1
CPU: Intel(R) Pentium(R) Dual CPU E2220 @ 2.40GHz 2.40GHz
Memory: 3.00 GB
在输入为100, 000数量级上,且输入的数据为随机值时,快速排序的效率优于插入排序
标签:style blog io ar color os sp for on
原文地址:http://www.cnblogs.com/hzhesi/p/4137111.html