Here is a Python function that evaluates a postfix expression using a stack:

```python
def evaluate_postfix(expression):
stack = []
for char in expression:
if char.isdigit():
stack.append(int(char))
else:
operand2 = stack.pop()
operand1 = stack.pop()
if char == '+':
result = operand1 + operand2
elif char == '-':
result = operand1 - operand2
elif char == '*':
result = operand1 * operand2
elif char == '/':
result = operand1 / operand2
stack.append(result)
return stack.pop()

# Test the function
print(evaluate_postfix('94*2/')) # Output: 18
```

Here is how the function works:

1. It initializes an empty stack.
2. It iterates over each character in the expression.
3. If the character is a digit, it converts it to an integer and pushes it onto the stack.
4. If the character is an operator, it pops the top two elements from the stack, performs the operation, and pushes the result back onto the stack.
5. After all characters in the expression have been processed, the function returns the top element of the stack, which is the result of the expression.

Question

Here is a Python function that evaluates a postfix expression using a stack:

```python
def evaluate_postfix(expression):
    stack = []
    for char in expression:
        if char.isdigit():
            stack.append(int(char))
        else:
            operand2 = stack.pop()
            operand1 = stack.pop()
            if char == '+':
                result = operand1 + operand2
            elif char == '-':
                result = operand1 - operand2
            elif char == '*':
                result = operand1 * operand2
            elif char == '/':
                result = operand1 / operand2
            stack.append(result)
    return stack.pop()

# Test the function
print(evaluate_postfix('94*2/'))  # Output: 18
```

Here is how the function works:

1. It initializes an empty stack.
2. It iterates over each character in the expression.
3. If the character is a digit, it converts it to an integer and pushes it onto the stack.
4. If the character is an operator, it pops the top two elements from the stack, performs the operation, and pushes the result back onto the stack.
5. After all characters in the expression have been processed, the function returns the top element of the stack, which is the result of the expression.

Knowee AI · Accepted Answer

Here is a Python function that evaluates a postfix expression using a stack:

```python
def evaluate_postfix(expression):
    stack = []
    for char in expression:
        if char.isdigit():
            stack.append(int(char))
        else:
            operand2 = stack.pop()
            operand1 = stack.pop()
            if char == '+':
                result = operand1 + operand2
            elif char == '-':
                result = operand1 - operand2
            elif char == '*':
                result = operand1 * operand2
            elif char == '/':
                result = operand1 / operand2
            stack.append(result)
    return stack.pop()

# Test the function
print(evaluate_postfix('94*2/'))  # Output: 18
```

Here is how the function works:

1. It initializes an empty stack.
2. It iterates over each character in the expression.
3. If the character is a digit, it converts it to an integer and pushes it onto the stack.
4. If the character is an operator, it pops the top two elements from the stack, performs the operation, and pushes the result back onto the stack.
5. After all characters in the expression have been processed, the function returns the top element of the stack, which is the result of the expression.

Question

Solution

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