索引：[LeetCode] Leetcode 题解索引 (C++/Java/Python/Sql)
Github:
https://github.com/illuz/leetcode
024. Swap Nodes in Pairs (Medium)
链接：
题目：https://oj.leetcode.com/problems/swap-nodes-in-pairs/
代码(github)：https://github.com/illuz/leetcode
题意：
把1个链表中的每对节点对换（不能只换值）。
分析：
直接摹拟便可。
开个前节点来做会比较方便。
用 Python 的异常处理和赋值会很方便。
代码：
C++:
class Solution {
public:
ListNode *swapPairs(ListNode *head) {
ListNode *newHead = new ListNode(0);
newHead->next = head;
ListNode *preNode = newHead, *curNode = head;
int cnt = 1;
while (curNode != NULL && curNode->next != NULL) {
// swap curNode and curNode->next
preNode->next = curNode->next;
curNode->next = preNode->next->next;
preNode->next->next = curNode;
// go over two nodes
preNode = curNode;
curNode = curNode->next;
}
head = newHead->next;
delete newHead;
return head;
}
};
Python:
class Solution:
# @param a ListNode
# @return a ListNode
def swapPairs(self, head):
dummy = ListNode(0)
dummy.next = head
cur = dummy
try:
while True:
pre, cur, nxt = cur, cur.next, cur.next.next
# change the position of cur and nxt
pre.next, cur.next, nxt.next = nxt, nxt.next, cur
# now cur is in the third place
except:
return dummy.next