Write the code in Java or C, use a stack and provide time complexity analysis to prove the algorithm is O(n) time complexity.

2. Given a string containing just the characters 'C', ')', '{', '}', '[' and '', determine if the input string is valid in O(n) time. The brackets must close in the correct order, "O)" and "O[]{}" are all valid but "(]" and "(D]" are not. Hint: use stack Example: Input: "(D)]" Input: "O[{}" Output: False Output: True