Python Answers

Section 6.9 of your textbook ("Debugging") lists three possibilities to consider if a function is not working.

Describe each possibility in your own words.

Define "precondition" and "postcondition" as part of your description.

Create your own example of each possibility in Python code. List the code for each example, along with sample output from trying to run it.

Word Count - 2

Given a sentence S, write a program to print the frequency of each word in S, where words are sorted in alphabetical order.

Input

The input will be a single line containing a string S.

Output

The output contains multiple lines, with each line containing a word and frequency of each word in the given string separated by ": ", where words are sorted in alphabetical order.

Explanation

For example, if the given sentence is "Hello world, welcome to python world", the output should be

Hello: 1

python: 1

to: 1

welcome: 1

world: 2

Simple Calculator - 2

Write a program to create a menu-driven calculator that performs basic arithmetic operations (+, -, *, /, and %).

Input

The input will be a single line containing two integers and operator(+, -, *, /, and %) similar to 3 + 5.

Output

If the given operator is "+", print the sum of two numbers.

If the given operator is "-", print the result of the subtraction of the two numbers.

If the given operator is "*", print the multiplication of the two numbers.

If the given operator is "/", print the result of the division of the two numbers.

If the given operator is "%", print the result of the modulus operation of the two numbers.

Part 1

As an exercise, use incremental development to write a function called hypotenuse that returns the length of the hypotenuse of a right triangle given the lengths of the other two legs as arguments. Record each stage of the development process as you go. (Downey, 2015)

After the final stage of development, print the output of hypotenuse(3, 4) and two other calls to hypotenuse with different arguments.

Include all of the following in your Learning Journal:

An explanation of each stage of development, including code and any test input and output.

The output of hypotenuse(3,4).

The output of two additional calls to hypotenuse with different arguments.

Part 2

Invent your own function that does some useful computation of your choosing. Do not copy the function from somewhere else. Use incremental development, and record each stage of the development process as you go. Finally, print output that demonstrates that the function works as you intended.

Include all of the following in your Learning Journal:

An explanation of each stage of development, including code and any test input and output.

The output of three calls to your function with different arguments.

Do Exercise 6.4 from your textbook using recursion and the is_divisible function from Section 6.4. Your program may assume that both arguments to is_power are positive integers. Note that every positive integer that has an exponent of 0 is a power of "1". This includes "0" and "1", itself.

After writing your is_power function, include the following test cases in your script to exercise the function and print the results:

print("is_power(10, 2) returns: ", is_power(10, 2))

print("is_power(27, 3) returns: ", is_power(27, 3))

print("is_power(1, 1) returns: ", is_power(1, 1))

print("is_power(10, 1) returns: ", is_power(10, 1))

print("is_power(3, 3) returns: ", is_power(3, 3))

Matrix Rotations

You are given a square matrix A of dimensions NxN. You need to apply the below given 3 operations on the matrix A.

Rotation: It is represented as R S where S is an integer in {90, 180, 270, 360, 450, ...} which denotes the number of degrees to rotate. You need to rotate the matrix A by angle S in the clockwise direction. The angle of rotation(S) will always be in multiples of 90 degrees.

Update: It is represented as U X Y Z. In initial matrix A (as given in input), you need to update the element at row index X and column index Y with value Z.

After the update, all the previous rotation operations have to be applied to the updated initial matrix.

Querying: It is represented as Q K L. You need to print the value at row index K and column index L of the matrix A. Input

The first line contains a single integer N.

Next N lines contain N space-separated integers Aij (i - index of the row, j - index of the column).

Next lines contain various operations on the array. Each operation on each line (Beginning either with R, U or Q).

-1 will represent the end of input.Output

For each Query operation print the element present at row index K and colum index L of the matrix in its current state.Explanation

For Input:

2

1 2

3 4

R 90

Q 0 0

Q 0 1

R 90

Q 0 0

U 0 0 6

Q 1 1

-1

Initial Matrix

1 2

3 4

For R 90, clockwise rotation by 90 degrees, the matrix will become

3 1

4 2

For Q 0 0, print the element at row index 0 and column index 0 of A, which is 3.

For Q 0 1, print the element at row index 0 and column index 1 of A, which is 1.

Again for R 90, clockwise rotation by 90 degrees, the matrix will become

4 3

2 1

For Q 0 0, print the element at row index 0 and column index 0 of A, which is 4.

For U 0 0 6, update the value at row index 0 and column index 1 in the initial matrix to 6. So the updated matrix will be,

6 2

3 4

After updating, we need to rotate the matrix by sum of all rotation angles applied till now(i.e. R 90 and R 90 => 90 + 90 => 180 degrees in clockwise direction).

After rotation the matrix will now become

4 3

2 6

Next for Q 1 1, print the element at row index 1 and column index 1 of A, which is 6.

output

3

1

4

6

Sample Input 1

2

1 2

3 4

R 90

Q 0 0

Q 0 1

R 90

Q 0 0

U 0 0 6

Q 1 1

-1

Sample Output 1

3

1

4

6

Sample Input 2

2

5 6

7 8

R 90

Q 0 1

R 270

Q 1 1

R 180

U 0 0 4

Q 0 0

-1

Sample Output 2

5

8

8

Sum of Non-Primes

Write a program to print the sum of non-primes in the given N numbers. The numbers which are not primes are considered as non-primes.

Input

The first line of input will contain a positive integer (N).

The following N lines will contain an integer in each line.

Output

The output should be the sum of non-primes in the given numbers.

Word Count - 2

Given a sentence S, write a program to print the frequency of each word in S, where words are sorted in alphabetical order.

Input

The input will be a single line containing a string S.

Output

The output contains multiple lines, with each line containing a word and frequency of each word in the given string separated by ": ", where words are sorted in alphabetical order.

Explanation

For example, if the given sentence is "Hello world, welcome to python world", the output should be

Hello: 1

python: 1

to: 1

welcome: 1

world: 2

You are given a square matrix A of dimensions NxN. You need to apply the below given 3 operations on the matrix A.

Rotation: It is represented as R S where S is an integer in {90, 180, 270, 360, 450, ...} which denotes the number of degrees to rotate. You need to rotate the matrix A by angle S in the clockwise direction. The angle of rotation(S) will always be in multiples of 90 degrees.

Update: It is represented as U X Y Z. In initial matrix A (as given in input), you need to update the element at row index X and column index Y with value Z.

After the update, all the previous rotation operations have to be applied to the updated initial matrix.

Querying: It is represented as Q K L. You need to print the value at row index K and column index L of the matrix A.

Input

The first line contains a single integer N.

Next N lines contain N space-separated integers Aij (i - index of the row, j - index of the column).

Next lines contain various operations on the array. Each operation on each line (Beginning either with R, U or Q).

-1 will represent the end of input.

Output

For each Query operation print the element present at row index K and colum index L of the matrix in its current state.