[LeetCode] 024. Swap Nodes in Pairs (Medium) (C++/Python)

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,nxt.next = nxt,nxt.next,cur # now cur is in the third place except: return dummy.next