链表快排

具体思路就是两个指针，一个指针i负责分出大小两部分，一个指针j负责遍历， i左边的值都小于等于val，右边值都大于val，递归分治。

#include <iostream>
#include <vector>
using namespace std;

struct ListNode {
  int val;
  ListNode *next;
  ListNode(int x) : val(x), next(NULL) {}
};

void LinkedListQuickSort(ListNode *&left, ListNode* &right) {
  if (left != right) {
    ListNode *i = left, *j = left->next;
    int val = i->val;
    while (j != right) {
      if (j->val > val) {
        j = j->next;
      }
      else {
        i = i->next;
        swap(i->val, j->val);
        j = j->next;
      }
    }
    swap(left->val, i->val);
    LinkedListQuickSort(left, i);
    LinkedListQuickSort(i->next, right);
  }
}

int main() {
  vector<int> data = {-1, 3, 5, 3, 2, 7, 8, 1, 0, 6};
  ListNode *head = new ListNode(10);
  ListNode *p = head, *q = NULL;
  for (int i = 0; i < 10; i++) {
    p->next = new ListNode(data[i]);
    p = p->next;
  }
  LinkedListQuickSort(head, q);
  while (head != NULL) {
    cout << head->val << " ";
    head = head->next;
  }
}

结果：