Traffic Light
Programming Basics · Python
TASK
Problem
Given traffic-light color `red`, `yellow`, or `green`, print `STOP`, `WAIT`, or `GO`.
EXAMPLE
Example
green
GO
LIMITS
Constraints
color ∈ {red, yellow, green}
LEARN
Theory for this problem
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`input()` reads data entered by the user. The result of `input()` is initially a string. Comparison operators `==`, `!=`, `<`, `>`, `<=`, `>=` compare values and produce `True` or `False`. `if` checks a condition and runs its block when the condition is true. `else` runs when the corresponding `if` condition is false. `print()` displays the program result. Print only what the problem statement requires.
**Connection to this task.** An `if` statement chooses a program branch from a Boolean condition. Comparisons produce `True` or `False`, and `elif` lets you test several mutually exclusive cases in order. The expression `'STOP'` shows how this idea is applied to the task data.
NEED HELP?
Hints
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['Compare the string with each valid color.']
ANSWER
Solution
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c = input()
if c == 'red':
print('STOP')
elif c == 'yellow':
print('WAIT')
else:
print('GO')