Given q number of queries, you need to perform operations on the stack. Queries are of three types 1, 2 and 3. If the operation is to push (1) then push the elements, if the operations is to pop (2) then pop the element and if it is Top (3), then print the element at the top of stack (If stack is empty, print “-1”, without quotes).
Input: Queries = 6 3 1 5 1 6 1 7 2 3 Output: -1 6 The first query is to print top, but since the stack is empty, so we print -1. Next three queries are to push 5, 6, and 7, so we pushed them on a stack. Next query is pop, so we popped 7 from a stack. Final query is to print the top, so 6 is there at the top and thus printed.
Approach: Stack can be used to perform the given operation. If the input for a query is 1, then take another input and push the element into the stack using push() function. If the input for a query is 2, then pop the element using pop() function in a stack. If the input for a query is 3, then print the top element using top() function.
Below is the implemenatation of the above aprpoach:
- Design a stack with operations on middle element
- Design a stack which can give maximum frequency element
- Design a stack that supports getMin() in O(1) time and O(1) extra space
- Design a stack to retrieve original elements and return the minimum element in O(1) time and O(1) space
- Design and Implement Special Stack Data Structure | Added Space Optimized Version
- Stack Permutations (Check if an array is stack permutation of other)
- Infix to Postfix using different Precedence Values for In-Stack and Out-Stack
- Find maximum in stack in O(1) without using additional stack
- Stack | Set 3 (Reverse a string using stack)
- Sort a stack using a temporary stack
- stack empty() and stack size() in C++ STL
- Stack in C++ STL
- stack top() in C++ STL
- stack emplace() in C++ STL
- stack swap() in C++ STL
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