Question

tracing code: need some explanation on how to trace this code.  

total= 0 found = 0 for ct in rage (10, -11, -3):        total += ct        if (ct<0) and (ct%2 ==0):             found += 1         print(ct, total) print(found)	ct	sum	Found	Question	output

Answer 1

Let's Understand the program first that what is happening--

1. Firstly, total variable is assigned 0 and found vairable is also assigned 0.
2. Next is the for loop in which the iterating variable is ct whose range is from 10 to -11 but with step decrease of -3. Step decrease means ct will be assigned values by decrement of 3. Values assigned to ct will be 10, 7, 4, 1, -2, -5, -8. If we further decrement by 3 then then next value is -11 but it can't be included.
3. Inside for loop first statement is increasing the value of total variable .
4. Then there is nested if inside for loop which checks whether ct is less than 0 and if ct is even and "and" is used in between both conditions so it means if condition will be validated if both conditions are true.
5. Then inside if there is the statement of incrementing the value of found by 1.
6. Then we come outside of if condition but we are still inside for loop there is statement to print ct and total.
7. Then we come outside for loop and there is the statement of the program to print the incremented value of found.

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Now, lets trace the program and calculate the output-

1. FIrst the ct is assigned value of 10 then it comes inside the loop and total variable increments and stores the value of ct that is 10, now the value of total variable is 10.
2. Now if conditions are checked with the value of ct and in case of ct=10 one condition satisfies but first condition does not satisfy as ct is not less than 0 so it does not go inside the if condition and then there is print statement which prints ct and total so the first output is [10,10].
3. Now ct is assigned value of 7 then it comes inside the loop and total variable increments and stores the value of (ct+total) that is 17, now the value of total variable is 17.
4. Now if conditions are checked with the value of ct and in case of ct=7 both condition does not satisfies so it does not go inside the if condition and then there is print statement which prints ct and total so the next output is [7,17].
5. Now ct is assigned value of 4 then it comes inside the loop and total variable increments and stores the value of (ct+total) that is 21, now the value of total variable is 21.
6. Now if conditions are checked with the value of ct and in case of ct=4 one condition does not satisfies and one does but both are not true so it does not go inside the if condition and then there is print statement which prints ct and total so the next output is [4,21].
7. Now ct is assigned value of 1 then it comes inside the loop and total variable increments and stores the value of (ct+total) that is 22, now the value of total variable is 22.
8. Now if conditions are checked with the value of ct and in case of ct=1 both condition does not satisfies so it does not go inside the if condition and then there is print statement which prints ct and total so the next output is [1,22].
9. Now ct is assigned value of -2 then it comes inside the loop and total variable increments and stores the value of (ct+total) that is 20, now the value of total variable is 20.
10. Now if conditions are checked with the value of ct and in case of ct=-2 both condition does satisfies so it goes inside the if condition and then the value of found increments by 1 so the value of found now is 1 and then we come out of print statement  and then there is print statement which prints ct and total so the next output is [-2,20].
11. Now ct is assigned value of -5 then it comes inside the loop and total variable increments and stores the value of (ct+total) that is 15, now the value of total variable is 15.
12. Now if conditions are checked with the value of ct and in case of ct=-5 one condition satisfies but one does not so it does not go inside the if condition and then there is print statement which prints ct and total so the next output is [-5,15].
13. Now ct is assigned value the last value of -8 then it comes inside the loop and total variable increments and stores the value of (ct+total) that is 7, now the value of total variable is 7.
14. Now if conditions are checked with the value of ct and in case of ct=-8 and  both condition does satisfies so it goes inside the if condition and then the value of found increments by 1 so the value of found now is 2 and then we come out of print statement  and then there is print statement which prints ct and total so the next output is [-8,7].
15. Now we come out of the for loop and the last statement of the program executes that is printing the value of found varaible that is 2.

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OUTPUT OF THE PROGRAM IS --