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| 1 | +// 1->2->3->4->5 |
| 2 | +// 2->1->4->3->5 |
| 3 | + |
| 4 | +const { ListNode, makeList } = require('./创建单链表'); |
| 5 | +let list = makeList([1, 2, 3, 4]); |
| 6 | + |
| 7 | +var swapPairs = function (head) { |
| 8 | + if (!head) return head; |
| 9 | + |
| 10 | + let k = 0, |
| 11 | + pre = head, |
| 12 | + cur = pre.next, |
| 13 | + lastEnd = null; // 上一个分组交换后的第二个元素 |
| 14 | + |
| 15 | + while (cur) { |
| 16 | + let temp = cur.next, |
| 17 | + front = pre, |
| 18 | + end = cur; |
| 19 | + |
| 20 | + end.next = front; |
| 21 | + front.next = temp; |
| 22 | + if (lastEnd) { |
| 23 | + lastEnd.next = end; // 指向当前循环内的分组交换后的第一个元素 |
| 24 | + } |
| 25 | + if (k === 0) { |
| 26 | + list.head = end; |
| 27 | + } |
| 28 | + |
| 29 | + if (!temp) { |
| 30 | + break; |
| 31 | + } |
| 32 | + pre = temp; |
| 33 | + cur = temp.next; |
| 34 | + lastEnd = front; |
| 35 | + k++; |
| 36 | + } |
| 37 | + return list.head; |
| 38 | +}; |
| 39 | + |
| 40 | +swapPairs(list.head); |
| 41 | +list.print(); |
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