OSU Recursive Function Python Codes

Description

Write a recursive function named is_subsequence that takes two string parameters and returns True if the first string is a subsequence of the second string, but returns False otherwise. We say that string A is a subsequence of string B if you can derive A by deleting zero or more letters from B without changing the order of the remaining letters. You can assume that neither string contains upper-case letters.

You may use default arguments and/or helper functions.

Your recursive function must not:

use any loops

use any variables declared outside of the function

use any mutable default arguments

The file must be named: is_subsequence.py

Criterion Long Description

is_subsequence method

Returns True if string is subsequence: 6 points

Takes into consideration punctuation and ignores case: 5 points

Has a recursive call: 5 points

Has a base case: 4 points

second prompt:

You are given a puzzle consisting of a row of squares that contain nonnegative integers, with a zero in the rightmost square. Keep in mind that it’s possible for other squares to contain a zero. You have a token that starts on the leftmost square. On each turn, the token can shift left or right a number of squares equal to the value in its current square, but is not allowed to move off either end. For example, if the row of squares contains these values: [2, 4, 5, 3, 1, 3, 1, 4, 0], then on the first turn the only legal move is to shift right two squares, because the starting square contains a 2, and the token can’t move off the left end. The goal is to get the token to the rightmost square (that contains zero). This row has a solution (more than one), but not all rows do. If we start with the row [1, 3, 2, 1, 3, 4, 0], then there is no way for the token to reach the rightmost square. Write a recursive function named row_puzzle that takes a list of integers as a parameter and returns True if the puzzle is solvable for that row, but returns False otherwise.

You may use default arguments and/or helper functions.

Your recursive function must not:

use any loops

use any variables declared outside of the function

use any mutable default arguments

The file must be named: row_puzzle.py

 

Criterion Long Description

row_puzzle function

Returns True if the puzzle is solvable for that row, False otherwise: 15 points

Has a recursive call: 15 points

Has a base case: 10 points