203. 移除链表元素 (二刷)

Author: w2xi

algorithms/remove-linked-list-elements.js

@@ -12,18 +12,22 @@
  * @return {ListNode}
  */
 var removeElements = function (head, val) {
-  // 1. 递归
-  let curr = head;
+  // 1. 迭代-方式一 (更好理解) (dummy node)
 
-  if (curr) {
-    curr.next = removeElements(curr.next, val);
-    if (curr.val === val) {
-      return curr.next;
+  let dummyNode = new ListNode(0, head);
+  let curr = dummyNode;
+
+  while (curr.next) {
+    if (val === curr.next.val) {
+      curr.next = curr.next.next;
+      continue;
     }
+    curr = curr.next;
   }
-  return curr;
 
-  // 2. 迭代 (dummy node)
+  return dummyNode.next;
+
+  // 2. 迭代-方式二 (dummy node)
 
   // let curr = head;
   // let dummyNode = new ListNode(-1);
@@ -40,4 +44,16 @@ var removeElements = function (head, val) {
   // }
 
   // return dummyNode.next;
+
+  // 3. 递归
+
+  // let curr = head;
+
+  // if (curr) {
+  //   curr.next = removeElements(curr.next, val);
+  //   if (curr.val === val) {
+  //     return curr.next;
+  //   }
+  // }
+  // return curr;
 };

vs-lt/203.移除链表元素.js

@@ -0,0 +1,49 @@
+/*
+ * @lc app=leetcode.cn id=203 lang=javascript
+ *
+ * [203] 移除链表元素
+ */
+
+// @lc code=start
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @param {number} val
+ * @return {ListNode}
+ */
+var removeElements = function(head, val) {
+  // 递归
+
+  // let curr = head;
+
+  // if (curr) {
+  //   curr.next = removeElements(curr.next, val);
+  //   if (val === curr.val) {
+  //     return curr.next;
+  //   }
+  // }
+  // return curr;
+
+  // 迭代
+
+  let dummyNode = new ListNode(0, head);
+  let curr = dummyNode;
+
+  while (curr.next) {
+    if (val === curr.next.val) {
+      curr.next = curr.next.next;
+      continue;
+    }
+    curr = curr.next;
+  }
+
+  return dummyNode.next;
+};
+// @lc code=end
+