add JS solution for 0027,0058,0234

solution/0027.Remove Element/Solution.js

@@ -0,0 +1,39 @@
+var removeElement3 = function (nums, val) {
+  let len = nums.length
+  if (len < 1) {
+    return 0
+  }
+
+  let i = 0
+  while (i < len) {
+    if (nums[i] === val) {
+      nums[i] = nums[len - 1]
+      len--
+    } else {
+      i++
+    }
+  }
+  return len
+};
+
+var removeElement2 = function (nums, val) {
+  let i = 0
+  for (let j = 0; j < nums.length; j++) {
+    if (nums[j] !== val) {
+      nums[i] = nums[j]
+      i++
+    }
+  }
+  return i
+}
+
+var removeElement = function (nums, val) {
+  let len = nums.length;
+  for (let i = 0; i < len; i++) {
+    if (nums[i] === val) {
+      nums.splice(i, 1);
+      i--;
+    }
+  }
+  return len;
+}

solution/0058.Length of Last Word/Solution.js

@@ -0,0 +1,16 @@
+var lengthOfLastWord = function (s) {
+  s = s.trim()
+  return s.length - s.lastIndexOf(" ") - 1
+};
+
+var lengthOfLastWord2 = function (s) {
+  let res = 0
+  for (let i = 0; i < s.length; i++) {
+    if (s[i] !== ' ' && (i === 0 || s[i - 1] === ' ')) {
+      res = 1
+    } else if (s[i] !== ' ') {
+      res++
+    }
+  }
+  return res
+}

solution/0234.Palindrome Linked List/Solution.js

@@ -0,0 +1,58 @@
+var isPalindrome2 = function (head) {
+  if (!head || !head.next) {
+    return true
+  }
+  let slow = head
+  let fast = head
+  while (fast !== null && fast.next !== null) {
+    slow = slow.next
+    fast = fast.next.next
+  }
+  if (fast !== null) {
+    slow = slow.next
+  }
+
+  let p = new ListNode(0)
+  while (slow !== null) {
+    let t = slow.next
+    slow.next = p.next
+    p.next = slow
+    slow = t
+  }
+
+  let left = head
+  let right = p.next
+  while (right !== null) {
+    if (left.val !== right.val) {
+      return false
+    }
+    left = left.next
+    right = right.next
+  }
+  return true
+};
+
+var isPalindrom3 = function (head) {
+  let arr = [];
+  let next = head;
+  while (next) {
+    arr.push(next.val);
+    next = next.next;
+  }
+  let len = Math.trunc(arr.length / 2);
+  for (let i = 0; i < len; i++) {
+    if (arr[i] !== arr[arr.length - 1 - i]) {
+      return false;
+    }
+  }
+  return true;
+}
+
+var isPalindrome = function (head) {
+  let arr = []
+  while (head) {
+    arr.push(head.val)
+    head = head.next
+  }
+  return arr.join('') === arr.reverse().join('')
+}