Given a string s containing only the characters '(', ')', '{', '}', '[', and ']', we need to determine if the input string is valid. An input string is considered valid if the following conditions are met:

You are given an integer array nums of length n. The task is to create a new array ans of length 2n such that ans[i] == nums[i] and ans[i + n] == nums[i] for 0 <= i < n (0-indexed). In simpler terms, the array ans is formed by concatenating two copies of the array nums.

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively. Merge nums1 and nums2 into a single array sorted in non-decreasing order.