leetCode/24.两两交换链表中的节点.html

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    <title>Document</title>
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  <body>
    <script>
      /**
       * Definition for singly-linked list.
       * function ListNode(val, next) {
       *     this.val = (val===undefined ? 0 : val)
       *     this.next = (next===undefined ? null : next)
       * }
       */
      function ListNode(val, next) {
        this.val = val === undefined ? 0 : val;
        this.next = next === undefined ? null : next;
      }
      var swapPairs = function (head) {
        if (!head || !head.next) return head;
        let newHead = new ListNode('head', head);
        let p_pre = newHead;
        let pre = p_pre.next;
        let cur = pre.next;
        while (pre && cur) {
          pre.next = cur.next;
          p_pre.next = cur;
          cur.next = pre;

          p_pre = pre;
          pre = pre.next;
          cur = pre ? pre.next : null;
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        return newHead.next;
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      let head = {
        val: 1,
        next: {
          val: 2,
          next: {
            val: 3,
            next: {
              val: 4,
              next: null
            }
          }
        }
      };
      head = {
        val: 1,
        next: {
          val: 2,
          next: {
            val: 3,
            next: {
              val: 4,
              next: {
                val: 5,
                next: null
              }
            }
          }
        }
      };
      console.log('swapPairs = ', swapPairs(head));
    </script>
  </body>
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