how to algorithm swap the contents of two variables using a third variables

1. Set up three variables, let's call them A, B, and C.

2. Assign the value of A to C. (C=A)
3. Assign the value of B to A. (A=B)
4. Assign the value of C to B. (B=C)
5. Print out A and B to confirm that their values have been swapped.

Here is an example algorithm in Python:

```
A = 5
B = 10

# swapping the variables

C = A
A = B
B = C

# print out the swapped values

print("A is now: ", A)
print("B is now: ", B)
```

Output:

```
A is now: 10
B is now: 5
```

To swap the contents of two variables using a third variable, you can follow these steps:

1. Declare three variables: `var1`, `var2`, and `temp`.

2. Assign values to `var1` and `var2` based on your requirements.

3. Assign the value of `var1` to `temp`.

```
temp = var1;
```

4. Assign the value of `var2` to `var1`.

```
var1 = var2;
```

5. Assign the value of `temp` to `var2`.

```
var2 = temp;
```

Here's an example code snippet in Python:

```
var1 = 5
var2 = 10

print("Before swapping:")
print("var1 =", var1)
print("var2 =", var2)

temp = var1
var1 = var2
var2 = temp

print("After swapping:")
print("var1 =", var1)
print("var2 =", var2)
```

Output:
```
Before swapping:
var1 = 5
var2 = 10
After swapping:
var1 = 10
var2 = 5
```

By following these steps, you'll successfully swap the contents of two variables using a third variable.