You're an avid bird watcher that keeps track of how many birds have visited your garden in the last seven days.
You have six tasks, all dealing with the numbers of birds that visited your garden.
For comparison purposes, you always keep a copy of last week's counts nearby, which were: 0, 2, 5, 3, 7, 8 and 4. Create a vector containing last week's counts:
last-week ;;=> [0 2 5 3 7 8 4]
today function to return how many birds visited your garden today. The bird counts are ordered by day, with the first element being the count of the oldest day, and the last element being today's count.
(def birds-per-day [2 5 0 7 4 1]) (today birds-per-day) ;;=> 1
inc-bird function to increment today's count:
(inc-bird birds-per-day) ;;=> [2 5 0 7 4 2]
day-without-birds? predicate function that returns
true if there was a day at which zero birds visited the garden; otherwise, return
(day-without-birds? birds-per-day) ;;=> true
n-days-count function that returns the number of birds that have visited your garden from the start of the week, but limit the count to the specified number of days from the start of the week.
(n-days-count birds-per-day 4) ;;=> 14
Some days are busier than others. A busy day is one where five or more birds have visited your garden.
busy-days function to return the number of busy days:
(busy-days birds-per-day) ;;=> 2
Over the last year, you've found that some weeks for the same, odd pattern, where the counts alternate between one and zero birds visiting. Implement the
odd-week? function that returns
true if the bird count pattern of this week matches the odd pattern:
(odd-week? [1 0 1 0 1 0 1]) ;;=> true