diff options
Diffstat (limited to 'racket/leetcode/lc-989-add-to-array-form.rkt')
| -rw-r--r-- | racket/leetcode/lc-989-add-to-array-form.rkt | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/racket/leetcode/lc-989-add-to-array-form.rkt b/racket/leetcode/lc-989-add-to-array-form.rkt new file mode 100644 index 0000000..c88bdc9 --- /dev/null +++ b/racket/leetcode/lc-989-add-to-array-form.rkt @@ -0,0 +1,24 @@ +#lang racket +(define/contract (add-to-array-form num k) + (-> (listof exact-integer?) exact-integer? (listof exact-integer?)) + (define rev-num (reverse num)) + (define raw-array-form + (cond [(= k 0) num] + [else + (for/fold ([sum-list '()] + [addend k] + [carry 0] + #:result sum-list) + ([place (append rev-num + (make-list (add1 (order-of-magnitude k)) 0))]) + (let* ([place-sum (+ place carry (modulo addend 10))] + [to-carry (quotient place-sum 10)] + [new-place (modulo place-sum 10)]) + (values (cons new-place sum-list) + (quotient addend 10) + to-carry)))])) + (match-define-values + (result _) (drop-common-prefix raw-array-form + (make-list (length raw-array-form) 0))) + (cond [(empty? result) '(0)] + [else result]))
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