排序算法-选择排序 Selection Sort

版本一

// Selection sort
// 选择排序
#include <iostream>
using namespace std;

void swap(int* a, int* b)
{
int temp = *a;
*a = *b;
*b = temp;
}

void SelectionSort(int a[], int size)
{
for (int i = 0; i < size; i++)
for (int j = i+1; j < size; j++)
if (a[j] < a[i])
swap(a[j], a[i]);
}

void print(int a[], int size)
{
for (int i = 0; i < size; i++)
cout << a[i] << " ";

cout << endl;
}

int main(int argc, char* argv[])
{
#if 0
int A[] = { 5,2,4,6,1,3 };
int size = sizeof(A)/sizeof(int);
#else // 假设个数未知
int size = 0;
cout << "Enter array size: ";
cin >> size;

cout << "Enter array elements: ";
int* A = new int[size];
int i = 0;
while ((cin >> A[i]) &&
(i < size) )
{
i++;
}

#endif

SelectionSort(A, size);

print(A, size);

delete[] A;
return 0;
}

版本二

#include <iostream>
using namespace std;

typedef int Item;
#define key(A) (A)
#define less(A, B) (key(A) < key(B))
#define exch(A, B) {Item t = A; A = B; B = t;}
#define compexch(A, B) if(less(B, A)) exch(A, B)

void print(int a[], int size)
{
for (int i = 0; i < size; i++)
cout << a[i] << " ";

cout << endl;
}

void selection_sort(Item a[], int size)
{
for (int i = 0; i < size; i++)
{
int min = i;
for (int j = i+1; j < size; j++)
if (less(a[j], a[min])) min = j;

exch(a[i], a[min]);
}
}

int main(int argc, char* argv[])
{
int A[] = { 8,7,6,5,4,3,2,1 };
int size = sizeof(A)/sizeof(int);

selection_sort(A, size);

print(A, size);
return 0;
}