Week 3 - You Try It
Solution Key

This page contains quick solutions to the mystery problems from You Try It #3. A video is available where each is explained in a little more detail.

Solutions

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n)
• In 1 or 2 sentences, what does this function do?
  • It adds up all of the numbers from 0 to howMany-1
  • If howMany is 5 this would return the sum of 0+1+2+3+4

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(1)
• In 1 or 2 sentences, what does this function do?
  • This method adds up the numbers from 0 to 9 regardless of what parameter is put in.
  • It always returns 45 and that takes the same amount of time to calculate every time.

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n)
• In 1 or 2 sentences, what does this function do?
  • This will return the same number as howMany.
  • It arrives at that value by adding 1 to the sum the number of times represented by howMany.

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n)
• In 1 or 2 sentences, what does this function do?
  • It returns the index of the first occurrence of item in the list named someList.
  • If the item does not occur in the list it returns -1.

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n)
• In 1 or 2 sentences, what does this function do?
  • It returns True or False indicating whether item was found in someList.

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n)
• In 1 or 2 sentences, what does this function do?
  • It returns the index of the last occurrence of item in the list named someList.
  • If the item does not occur in the list it returns -1.

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n)
• In 1 or 2 sentences, what does this function do?
  • It returns the index of the first occurrence of item in the list named someList.
  • If the item does not occur in the list it returns -1.
• Yes, this does the exact same thing as method 4.

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n²)
• In 1 or 2 sentences, what does this function do?
  • NOTE: A meaningful description to this one is hard because it makes little sense.
  • It returns a number which is n+2y where
    • n is the length of someList and
    • y s the number of "pairs" of matching values

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n²)
• In 1 or 2 sentences, what does this function do?
  • It counts the number of unique matching pairs in someList.

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n)
• In 1 or 2 sentences, what does this function do?
  • It returns True if any of the first five items in the list match with some other item in the remainder of the list
  • Note: It will crash if there are not at least 7 items in the list

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(n)
• In 1 or 2 sentences, what does this function do?
  • It will count and return how many times item1 and item2 are found in the list.

• What is the Big-Oh value (O(1), O(n) or O(n²)
  • O(1)
• In 1 or 2 sentences, what does this function do?
  • It will count and return how many times item is found in the first five items of the list.