Leetcode tasks

• [09] Merge k sorted lists
• [10] Search in rotated sorted array
• [13] Group anagrams
• [14] Maximum subarray
• [17] Merge intervals
• [18] Insert intervals
• [23] Word search
• [24] Decode ways
• [29] Construct Binary Tree from Preorder and Inorder Traversal
• [30] Best Time to Buy and Sell Stock
• [31] Binary Tree Maximum Path Sum
• [32] Valid Palindrome