Question-14

GATE-2023 (modified)
Python programming
recursion

Consider the following program:

def main():
    f1()
    f2(2)
    f3()
    return 0

def f1():
    return 1

def f2(X):
    f3()
    if X == 1:
        return f1()
    else:
        return X * f2(X - 1)

def f3():
    return 5

main()

Which one of the following options represents the activation tree corresponding to the main function?

  • main
├── f1
├── f2
│   ├── f3
│   └── f2
│       ├── f3
│       └── f1
└── f3

  • main
├── f1
├── f2
│   ├── f3
│   └── f1
└── f3

  • main
├── f1
├── f2
│   ├── f3
│   └── f1
└── 

  • main
├── f1
├── f2
│   ├── f3
│   ├── f2
│   └── f1
└── f3
  • main calls f1, f2 and f3. and f1 and f3 returns.
  • In f2, f3 is called and f2 is called again with X=1 as the condition goes to else part.
  • In the new f2, f3 is called and f1 is called end the calls end there.