Am I an insignificant array?

Question

An insignificant array is an array of positive integers, where the absolute differences between consecutive elements are all smaller than or equal to 1.

For example, the following array is insignificant:

[1, 2, 3, 4, 3, 4, 5, 5, 5, 4]

Because the corresponding (absolute) differences are:

[1, 1, 1, 1, 1, 1, 0, 0, 1]

Which are all smaller than or equal to 1.

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Your task is to determine whether a given array of integers is insignificant.

• You may assume that the array always contains at least two elements.
• Standard input and output rules apply. You may take input (and output) in any reasonable format.
• Default Loopholes are forbidden.
• The truthy / falsy values have to be distinct and consistent.
• This is code-golf, so shortest answer in bytes wins.

Test cases

Input -> Output

[1, 2, 3, 4, 3, 4, 5, 5, 5, 4] -> true
[1, 2, 3, 4, 5, 6, 7, 8, 9, 8] -> true
[3, 3, 3, 3, 3, 3, 3]          -> true
[3, 4, 4, 4, 3, 3, 3, 4, 4, 4] -> true
[1, 2, 3, 4]                   -> true 
[5, 4, 3, 2]                   -> true 
[1, 3, 5, 7, 9, 7, 5, 3, 1]    -> false
[1, 1, 1, 2, 3, 4, 5, 6, 19]   -> false
[3, 4, 5, 6, 7, 8, 7, 5]       -> false
[1, 2, 4, 10, 18, 10, 100]     -> false
[10, 20, 30, 30, 30]           -> false

I used the values true and false.

Answer 1

Python 3, 49 bytes

lambda l:all(abs(j-i)<=1 for i,j in zip(l,l[1:]))

Answer 2

Pyth, 15 12 bytes

Works pretty simply. T or 10 as a boolean is True

V.+Q=&T<N2)T

Explanation:

V.+Q        In the difference map of the input...
    =&T<N2) T = T && the current item is less than 2, and close the loop
T           Print J

Test Suite

Answer 3

Scheme - 89 bytes

(define (f n) (if (not (empty? n)) (and (<= (abs (- (cadr n) (car n))) 1) (f (cdr n))) 1)

Answer 4

Casio-Basic, 28 bytes

judge(max(abs(⊿list(n)))<2

It's nice that the fx-CP400 has a built-in for cumulative differences. Not so nice that you need to use judge to force it to check whether the resulting value is less than 2.

27 bytes for the function (⊿ is two bytes), +1 to enter n in the argument list.

Answer 5

Pxem, Filename: 40 bytes + Content: 0 bytes = 40 bytes.

• Filename (escaped): ._\001.-.c._.t.w\001.-._.c.m.-\001.x.d.a.t.c.aY.o
• Content: empty

Usage

Input is from STDIN; output from STDOUT. First positive integer N for input represents number of items in list. Then integers c1, c2, ..., cN represents each item of the list. Each input has to be separated by one or more s.

An output of Y represents truthy, and no output falsey.

Input example

List [1, 2, 3, 4, 3, 4, 5, 5, 5, 4] is:

10
1 2 3 4 3 4 5 5 5 4

With comments

XX.z
.a._\001.-.cXX.z # push N; decrement it
.a._.tXX.z # push c1; heap<-c1
.a.w\001.-XX.z # while N!=0; do N--
  .a._.c.m.-\001.xXX.z # push ci; if abs(ci-heap); then
    .a.dXX.z # exit
  .a.aXX.z # fi
  .a.tXX.z # heap=ci
.a.c.aXX.z # done
.aY.oXX.z # putchar o
.a

Link

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Answer 6

Factor, 28 bytes

[ [ - [-1,1]? ] monotonic? ]

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monotonic? is a combinator that tests if a quotation returns true for every pair of adjacent elements in a sequence.

• - Subtract.
• [-1,1]? Is it between -1 and 1 inclusive? (This is just the name of a word, like most everything in Factor.)

Answer 7

Arturo, 36 bytes

$[a][n:a\0every? a'x[2>abs n-x n:x]]

Try it

Answer 8

Stax, 8 bytes

┘ε≡}◄ï╖Z

Run and debug it

Link includes all test cases.

Unpacked:

Stax, 10 bytes

:-{|a2<m:*

Run and debug it

:-          # pairwise differences/deltas
  {     m   # mapped by
   |a       # absolute value of n
     2<     # is less than 2
         :* # product of array (essentially all(a))

Answer 9

Kamilalisp, 31 bytes (APL385 SBCS)

$(∧?∘⌹‡⍡ 2 $(> 2)∘abs∘$(⌿⊙← -))

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