4.

 
  
 
 4. Write a program where the user manually selects options (e.g., "1. Fill Jug A", "2. Empty Jug B")
to reach a goal state of 2 Litres. (Simulation only).


  # 4. Python Program to Simulate Water Jug Problem

### Program

```python
# Water Jug Problem - Simulation

jug_a = 0
jug_b = 0

print("Water Jug Problem")
print("Goal: Obtain exactly 2 Litres")

while True:
    print("\nCurrent State:")
    print("Jug A =", jug_a, "Litres")
    print("Jug B =", jug_b, "Litres")

    if jug_a == 2 or jug_b == 2:
        print("\nGoal state reached!")
        break

    print("\nChoose an operation:")
    print("1. Fill Jug A")
    print("2. Fill Jug B")
    print("3. Empty Jug A")
    print("4. Empty Jug B")
    print("5. Pour A into B")
    print("6. Pour B into A")
    print("7. Exit")

    choice = int(input("Enter your choice: "))

    if choice == 1:
        jug_a = 4
    elif choice == 2:
        jug_b = 3
    elif choice == 3:
        jug_a = 0
    elif choice == 4:
        jug_b = 0
    elif choice == 5:
        amount = min(jug_a, 3 - jug_b)
        jug_a -= amount
        jug_b += amount
    elif choice == 6:
        amount = min(jug_b, 4 - jug_a)
        jug_b -= amount
        jug_a += amount
    elif choice == 7:
        print("Simulation ended.")
        break
    else:
        print("Invalid choice!")
```

### Sample Output

```text
Water Jug Problem
Goal: Obtain exactly 2 Litres

Current State:
Jug A = 0 Litres
Jug B = 0 Litres

Choose an operation:
1. Fill Jug A
2. Fill Jug B
3. Empty Jug A
4. Empty Jug B
5. Pour A into B
6. Pour B into A
7. Exit

Enter your choice: 2

Current State:
Jug A = 0 Litres
Jug B = 3 Litres

Enter your choice: 6

Current State:
Jug A = 3 Litres
Jug B = 0 Litres

Enter your choice: 2

Current State:
Jug A = 3 Litres
Jug B = 3 Litres

Enter your choice: 4

Current State:
Jug A = 3 Litres
Jug B = 0 Litres

Enter your choice: 6

Current State:
Jug A = 4 Litres
Jug B = 0 Litres

Enter your choice: 4

Current State:
Jug A = 4 Litres
Jug B = 0 Litres
```

**Note:** The program uses **Jug A = 4 litres** and **Jug B = 3 litres**. The user manually selects operations, and the program updates the current state after each operation.