/*
* description: 快速排序示例
* writeby: nick
* date: 2012-10-23 16:16
*
*/
#include <iostream>
#include <stack>
using namespace std;
//递归版本
void quicksort(int a[], int l, int r)
{
int mid = a[(l+r) / 2];
int lwalker = l, rwalker = r;
while(lwalker < rwalker)
{
while(a[lwalker] < mid) lwalker++;
while(a[rwalker] > mid) rwalker--;
if(lwalker <= rwalker)
{
int tmp = a[lwalker];
a[lwalker] = a[rwalker];
a[rwalker] = tmp;
lwalker++;
rwalker--;
}
}
if(lwalker < r) quicksort(a, lwalker, r);
if(rwalker > l) quicksort(a, l, rwalker);
}
inline void push2(stack<int> &s, int l, int r)
{
s.push(r);
s.push(l);
}
//非递归,使用栈
void qsort(int a[], int l, int r)
{
stack<int> s;
push2(s, l, r);
int lwalker, rwalker, mid;
while(!s.empty())
{
int left = s.top(); s.pop();
int right = s.top(); s.pop();
lwalker = left;
rwalker = right;
mid = a[(lwalker+rwalker)/2];
while(lwalker < rwalker)
{
while(a[lwalker] < mid) lwalker++;
while(a[rwalker] > mid) rwalker--;
if(lwalker <= rwalker)
{
int tmp = a[lwalker];
a[lwalker] = a[rwalker];
a[rwalker] = tmp;
lwalker++;
rwalker--;
}
}
if(lwalker < right) push2(s, lwalker, right);
if(rwalker > left) push2(s, left, rwalker);
}
}
int main()
{
int a[10] = {0, 6,4,2,8,1,5,3,7,9};
//quicksort(a, 0, 9);
qsort(a, 0, 9);
for(int i=0; i<10; i++)
cout << a[i] << " ";
return 0;
}