161. Implement a function to find the longest valid parentheses substring using a stack.

162. Write a function to merge overlapping intervals using a stack.

163. Implement a function to generate all unique permutations of a string using a stack.

164. Write a function to check if a given stack can be sorted with another stack.

165. Implement a function to create a stack from a linked list.

166. Write a function to evaluate a complex expression with nested operations.

167. Implement a function to find the maximum product of three elements in a stack.

168. Write a function to perform a preorder traversal of a binary tree using a stack.

169. Implement a function to find the maximum depth of nested expressions using a stack.

170. Write a function to generate all possible arrangements of parentheses.

171. Implement a function to create a stack that supports range updates.

172. Write a function to check if a stack can be sorted with limited operations.

173. Implement a function to calculate the longest increasing subsequence using a stack.

174. Write a function to find the longest balanced substring of brackets using a stack.

175. Implement a function to check if two stacks have the same elements in the same order.

176. Write a function to find the longest decreasing subsequence of integers in a stack.

177. Implement a function to merge K sorted stacks into a single sorted stack.

178. Write a function to find the longest common subsequence between two strings using a stack.

179. Implement a function to evaluate a mathematical expression with nested operations.

180. Write a function to find the first non-repeating character in a stack.

181. Implement a function to check if a stack is a permutation of another stack.

182. Write a function to find the shortest valid parentheses substring.

183. Implement a function to calculate the maximum area of a rectangle in a histogram.

184. Write a function to find the maximum sum of a contiguous subarray in a stack.

185. Implement a function to check if a stack can be sorted with a limited number of auxiliary stacks.

186. Write a function to find the longest increasing subsequence using a stack.

187. Implement a function to create a stack that maintains the order of elements based on a custom comparator.

188. Write a function to evaluate an expression in postfix notation with multiple operators.

189. Implement a function to find the smallest element that appears only once in a stack.

190. Write a function to check if a stack can be sorted using bubble sort.

191. Implement a function to calculate the maximum depth of nested parentheses using a stack.

192. Write a function to generate all possible permutations of a set using a stack.

193. Implement a function to check if a stack can be sorted with limited operations.

194. Write a function to find the longest balanced substring of parentheses using a stack.

195. Implement a function to create a stack that supports conditional operations.

196. Write a function to evaluate a complex expression using a stack.

197. Implement a function to merge overlapping intervals using a stack.

198. Write a function to find the maximum area of a rectangle in a histogram using a stack.

199. Implement a function to find the longest palindrome substring in a stack.