用双链表快速排序

#include<cstdio>
#include<fstream>
#include<iostream>
using namespace std;

struct Node {
	int data = 0;
	Node* l = NULL, * r = NULL;
}*head = NULL , *tail = NULL;

void N_swap(Node* a, Node* b) {
	int tmp = a->data;
	a->data = b->data;
	b->data = tmp;
}

void quick_sort(Node *h, Node* t,int l, int r) {
	if (l < r) {
		Node* p = h, * q = t;
		int x = h->data, p1 = l , q1 = r;

		while (p1 < q1) {
			if (p->data == q->data) {
				q = q->l, q1--;
				continue;
			}
			while (p->r && p->data < x) p = p->r, p1++;
			while (q->l && q->data > x) q = q->l, q1--;
			if (p1 < q1) N_swap(p, q);
		}

		quick_sort(h, q, l, q1), quick_sort(q->r, t, q1 + 1, r);
	}
}

int main() {
	ifstream ifile("in.txt");
	int x;

	while (ifile >> x) {
		Node* p = new Node;
		p->data = x;

		if (head) {
			tail->r = p;
			p->l = tail;
		}
		else head = p;
		tail = p;
	}

	int l = 0;
	for (Node* i = head; i; i = i->r) cout << i->data << " ",l++;
	puts("");

	quick_sort(head, tail, 1, l);

	for (Node* i = head; i; i = i->r) cout << i->data << " ";
	puts("");

	return 0;
}