3-Stack

Stack Data Structure

Identification of Problems

How to identify problems to implement the stack data structure -

• Most of the question based on Array or Heap.
• In brute force O(n²) when one loop is dependent on another loop.

for i in range(n):
    for j in range(i, n):

• Here j is going either 0 to i, i to 0, i to n or n to i.