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Diffstat (limited to 'racket/leetcode/lc-1037-boomerang.rkt')
| -rw-r--r-- | racket/leetcode/lc-1037-boomerang.rkt | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/racket/leetcode/lc-1037-boomerang.rkt b/racket/leetcode/lc-1037-boomerang.rkt new file mode 100644 index 0000000..fd95695 --- /dev/null +++ b/racket/leetcode/lc-1037-boomerang.rkt @@ -0,0 +1,21 @@ +#lang racket +(define/contract (is-boomerang points) + (-> (listof (listof exact-integer?)) boolean?) + (match points + [(list-no-order a b c) #:when (equal? a b) #false] ; Are any two points the same? + [(list (list x _) (list x _) (list x _)) #false] ; Are they on a horizontal line? + [(list (list _ y) (list _ y) (list _ y)) #false] ; Are they on a vertical line? + [(list-no-order (list x1 _) (list x2 _) (list x3 _)) ; Are two points on a horizontal line, + #:when (and (= x1 x2) ; but the third point isn't? + (not (= x1 x3))) #true] + [(list-no-order (list _ y1) (list _ y2) (list _ y3)) ; Are two points on a vertical line, + #:when (and (= y1 y2) ; but the third point isn't? + (not (= y1 y3))) #true] + [(list (list x1 y1) (list x2 y2) (list x3 y3)) ; If none of the special cases apply, + (let ([m (/ (- y2 y1) (- x2 x1))]) ; calculate the slope between two points + (not (= y3 (+ y1 (* m (- x3 x1))))))])) ; and see if the line passes through the third + +(is-boomerang '((1 1) (2 3) (3 2))) +(is-boomerang '((1 1) (2 2) (3 3))) +(is-boomerang '((0 0) (0 2) (2 1))) +(is-boomerang '((0 0) (1 1) (1 1)))
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