finish 0125

README.md

@@ -31,6 +31,7 @@ since 2021.10.10 / Benben
 - 0053.Maximum SubArray
 - 0104.Maximum Depth of Binary Tree
 - 0111.Minimum Depth of Binary Tree
+- 0125.Valid Palindrome
 - 0144.Binary Tree PreOrder Traversal
 - 0206.Reverse Linked List
 - 0226.Invert Binary Tree

interview/50/04-mergeKSortedLists.js

@@ -1,2 +1,39 @@
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode[]} lists
+ * @return {ListNode}
+ */
+var mergeKLists = function(lists) {
+  const mergeTwoLists = (l1, l2) => {
+    if (!l1 || !l2) return l1 || l2
+    let listNode = new ListNode
+    let cur = listNode
+    while(l1 && l2) {
+      if(l1.val > l2.val) {
+        cur.next = l2
+        l2 = l2.next
+      } else {
+        cur.next = l1
+        l1 = l1.next
+      }
+      cur = cur.next
+    }
+    cur.next = l1 || l2
+    return listNode.next
+  }
+
+  let root = lists[0];
+  for (let i = 1; i < lists.length; i++) {
+    root = mergeTwoLists(root, lists[i]);
+  }
+
+  return root || null;
+};
 
 // leetcode 0023

interview/50/08-kthSmallestElementInBST.js

@@ -0,0 +1,2 @@
+
+// leetcode 0230

interview/50/09-maxAreaOfIsland.js

@@ -0,0 +1,2 @@
+
+// leetcode 695

interview/50/10-reduceString.js

@@ -0,0 +1,9 @@
+
+
+// Input: "CABADCBD"
+// Output: ""
+// Explanation: "CABADCBD" -> "CADCBD" -> "CABD" -> "CD" -> ""
+
+// Input: "ACBD"
+// Output: "ACBD"
+// Explanation: "A" 和 "B" 以及 "C" 和 "D" 均沒有相鄰，無法轉態

leetcode-easy/0053-maximum-subarray.js

@@ -5,19 +5,18 @@
 var maxSubArray = function(nums) {
   if (nums.length === 0) return nums
 
-  let cur = nums[0]
-  let curMax = 0
-  let res = cur
+  let cur = 0
+  let max = -Infinity
 
-  for (let i = 1; i < nums.length; i++) {
-    curMax = Math.max(nums[i], cur + nums[i])
-    cur = curMax
-    res = Math.max(res, curMax)
+  for (let i = 0; i < nums.length; i++) {
+    cur = Math.max(nums[i], cur + nums[i])
+    max = Math.max(cur, max)
   }
 
-  return res
+  return max
 };
 
+
 // 2022/05/09 done.
-// Runtime: 109 ms, faster than 48.46% of JavaScript online submissions for Maximum Subarray.
-// Memory Usage: 50.4 MB, less than 48.90% of JavaScript online submissions for Maximum Subarray.
+// Runtime: 95 ms, faster than 68.36% of JavaScript online submissions for Maximum Subarray.
+// Memory Usage: 50.2 MB, less than 73.28% of JavaScript online submissions for Maximum Subarray.

leetcode-easy/0125-valid-palindrome.js

@@ -0,0 +1,24 @@
+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+var isPalindrome = function(s) {
+  let str = s
+    .toLowerCase()
+    .replace(/[^a-z0-9]/g, '')
+
+  let left = 0
+  let right = str.length - 1
+  while (left <= right) {
+    if (str[left] !== str[right]) {
+      return false
+    }
+    left++
+    right--
+  }
+  return true
+};
+
+// 2022/05/11 done.
+// Runtime: 110 ms, faster than 36.67% of JavaScript online submissions for Valid Palindrome.
+// Memory Usage: 44.2 MB, less than 82.99% of JavaScript online submissions for Valid Palindrome.