41. Implement a function to generate all subsets of a set using a stack.
42. Write a function to find the first non-repeating character in a stack.
43. Implement a function to calculate the maximum product of three elements in a stack.
44. Write a function to perform a level-order traversal of a binary tree using a stack.
45. Implement a function to merge overlapping intervals using a stack.
46. Write a function to find the longest palindrome substring in a stack.
47. Implement a function to create a stack that supports range updates.
48. Write a function to find the total number of distinct elements in a stack.
49. Implement a function to find the largest rectangle area in a histogram represented by a stack.
50. Write a function to perform a preorder traversal of a binary tree using a stack.
51. Implement a function to calculate the sum of the first N elements in a stack.
52. Write a function to find the longest consecutive sequence of integers in a stack.
53. Implement a function to check if two stacks are equivalent under different orderings.
54. Write a function to find the largest prime number in a stack.
55. Implement a function to evaluate a mathematical expression in infix notation.
56. Write a function to calculate the total sum of elements in a stack.
57. Implement a function to find the minimum height of a binary search tree using a stack.
58. Write a function to create a stack that maintains a frequency count of elements.
59. Implement a function to find the largest element that appears only once in a stack.
60. Write a function to find the longest increasing subsequence using a stack.
61. Implement a function to find the number of pairs of elements in a stack that sum to a target value.
62. Write a function to check if a stack can be sorted using a single auxiliary stack.
63. Implement a function to find the longest balanced substring of parentheses.
64. Write a function to create a stack from an array.
65. Implement a function to evaluate a postfix expression with multiple operands.
66. Write a function to find the maximum area of a rectangle in a histogram using a stack.
67. Implement a function to calculate the product of all elements in a stack.
68. Write a function to check if a given stack can be sorted with another stack.
69. Implement a function to find the maximum depth of nested parentheses using a stack.
70. Write a function to generate all possible subsets of a given set using a stack.
71. Implement a function to find the longest common substring using a stack.
72. Write a function to check if a given stack is a palindrome.
73. Implement a function to perform a postorder traversal of a binary tree using a stack.
74. Write a function to evaluate a complex expression using a stack.
75. Implement a function to create a stack that supports range queries.
76. Write a function to find the maximum difference between any two elements in a stack.
77. Implement a function to check if a stack can be sorted using a single auxiliary stack.
78. Write a function to find the longest increasing subsequence of integers in a stack.
79. Implement a function to generate all possible permutations of a string using a stack.
80. Write a function to find the total number of valid configurations of a stack.