diff options
Diffstat (limited to 'racket/leetcode/lc-228-summary-ranges.rkt')
| -rw-r--r-- | racket/leetcode/lc-228-summary-ranges.rkt | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/racket/leetcode/lc-228-summary-ranges.rkt b/racket/leetcode/lc-228-summary-ranges.rkt new file mode 100644 index 0000000..9140895 --- /dev/null +++ b/racket/leetcode/lc-228-summary-ranges.rkt @@ -0,0 +1,27 @@ +#lang racket +(define (summary-ranges nums) + (define range-pairs + (cond + [(empty? nums) '()] + [(empty? (cdr nums)) (list (cons (car nums) (car nums)))] + [else (for/fold ([ranges '()] + [open-pair (first nums)] + [prev-num (first nums)] + #:result (append ranges (list (cons open-pair prev-num)))) + ([i (cdr nums)]) + (cond [(= (add1 prev-num) i) + (values ranges + open-pair + i)] + [else + (values (append ranges (list (cons open-pair prev-num))) + i + i)]))])) + (for/list ([p (in-list range-pairs)]) + (cond [(= (car p) (cdr p)) (format "~a" (car p))] + [else (format "~a->~a" (car p) (cdr p))]))) + +(summary-ranges '(0 1 2 4 5 7)) +(summary-ranges '(0 2 3 4 6 8 9)) +(summary-ranges '()) +(summary-ranges '(0))
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