""" Output: Enter a Postfix Equation (space separated) = 5 6 9 * + Symbol | Action | Stack ----------------------------------- 5 | push(5) | 5 6 | push(6) | 5,6 9 | push(9) | 5,6,9 | pop(9) | 5,6 | pop(6) | 5 * | push(6*9) | 5,54 | pop(54) | 5 | pop(5) | + | push(5+54) | 59 Result = 59 """ import operator as op def solve(post_fix): stack = [] div = lambda x, y: int(x / y) # noqa: E731 integer division operation opr = { "^": op.pow, "*": op.mul, "/": div, "+": op.add, "-": op.sub, } # operators & their respective operation # print table header print("Symbol".center(8), "Action".center(12), "Stack", sep=" | ") print("-" * (30 + len(post_fix))) for x in post_fix: if x.isdigit(): # if x in digit stack.append(x) # append x to stack # output in tabular format print(x.rjust(8), ("push(" + x + ")").ljust(12), ",".join(stack), sep=" | ") else: b = stack.pop() # pop stack # output in tabular format print("".rjust(8), ("pop(" + b + ")").ljust(12), ",".join(stack), sep=" | ") a = stack.pop() # pop stack # output in tabular format print("".rjust(8), ("pop(" + a + ")").ljust(12), ",".join(stack), sep=" | ") stack.append( str(opr[x](int(a), int(b))) ) # evaluate the 2 values popped from stack & push result to stack # output in tabular format print( x.rjust(8), ("push(" + a + x + b + ")").ljust(12), ",".join(stack), sep=" | ", ) return int(stack[0]) if __name__ == "__main__": Postfix = input("\n\nEnter a Postfix Equation (space separated) = ").split(" ") print("\n\tResult = ", solve(Postfix))