leetcode -removeLinkedListElements

Leetcode题解之 —— 移除链表元素

思路

---

方法一: 转化为数组

• 通过filter、map高阶API解决

方法二: 修改next指针

• 创建firstNode节点, 指向head
• 两个指针lastNode、currentNode
  • 前者指向firstNode, 表示上一个节点
  • 后者指向head, 当前遍历的节点

题解

---

数组解法:

const cache = [];
let current = head;

while (current) {
  cache.push(new ListNode(current.val));
  current = current.next;
}

if (!cache.length) {
  return null;
}

const temp = cache
  .filter((v) => v.val !== val)
  .map((v, i, self) => {
    v.next = self[i + 1];

    return v;
  })

if (!temp.length) {
  return null;
}

return temp[0];

指针解法:

/**
 * @param {ListNode} head
 * @param {number} val
 * @return {ListNode}
 */
var removeElements = function (head, val) {
  const firstNode = new ListNode(0);
  firstNode.next = head;

  let [lastNode, currentNode] = [firstNode, head];

  while (currentNode) {
    if (currentNode.val === val) {
      lastNode.next = currentNode.next;
    } else {
      lastNode = currentNode;
    }
    currentNode = currentNode.next;
  }

  return firstNode.next || null;
};