Monotone sequence beatitude

Question

Provided that the input is a monotone sequence of three or more integers:

Output -2 if the sequence strictly decreases. Example: [7,4,3,2]
Output -1 if the sequence monotone decreases but is neither strict nor constant. Example: [6,5,5]
Output 0 if the sequence is constant. Example: [0,0,0]
Output +1 if the sequence monotone increases but is neither strict nor constant. Example: [-1,2,2,2,4]
Output +2 if the sequence strictly increases. Example: [0,1,2]

I/O format is flexible. Standard loopholes apply.

If the sequence is [-1,2,3,2,4], is it considered increasing ? — gobes, Nov 14 at 9:57

Command Master · Accepted Answer · 2023-11-14 00:31:37Z

10

05AB1E, 8 7 6 bytes

¥.±Z+W

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¥      deltas
.±     sign
Z      maximum without popping
+      add (vectorized)
W      minimum

edited Nov 14 at 0:31

answered Nov 13 at 23:43

Command Master

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chunes · Accepted Answer · 2023-11-14 00:06:42Z

6

Uiua, 11 bytes

⊢+⇌.⊝±≡/-◫2

Try it!

Port of Command Master's 05AB1E answer.

⊢+⇌.⊝±≡/-◫2
      ≡/-◫2  # deltas
     ±       # sign
    ⊝        # deduplicate
   .         # duplicate
  ⇌          # reverse
 +           # add
⊢            # first

answered Nov 14 at 0:06

chunes

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Nick Kennedy · Accepted Answer · 2023-11-14 00:19:02Z

6

Jelly, 6 bytes

IṠQ.ịS

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Port of Command Master's 05AB1E answer. A monadic link taking a list of integers and returning an integer.

Explanation

I      | Increments
 Ṡ     | Signs
  Q    | Uniquify
   .ị  | Last and first
     S | Sum

answered Nov 14 at 0:19

Nick Kennedy

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\$\begingroup\$ I think uniquify is not necessary Try it online! \$\endgroup\$
– pajonk
Nov 14 at 7:05
\$\begingroup\$ @pajonk it is if the input is something like [1,2,2,3] \$\endgroup\$
– Nick Kennedy
Nov 14 at 7:34
\$\begingroup\$ Ah, I get it now. It's "Last and first" (as described) not min and max. \$\endgroup\$
– pajonk
Nov 14 at 8:25

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Arnauld · Accepted Answer · 2023-11-15 12:45:13Z

JavaScript (ES6), 47 bytes

a=>(a.reduce((p,v)=>(a|=p<v?5:p>v?-2:3,v)),a%3)

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Method

Because the input array a contains at least 3 elements, it is guaranteed to be evaluated to \$0\$ when coerced to an integer. So we can safely re-use it as a signed 32-bit mask.

For each pair of consecutive elements \$(p,\:v)\$ in the input array, we apply to a a bitwise OR with:

\$5\$ if \$p<v\$
\$-2\$ if \$p>v\$
\$3\$ if \$p=v\$

These values were chosen such that the expected output in \$[-2\dots2]\$ is obtained by reducing the final bitmask modulo \$3\$.

List of cases

Because the sequence is monotone, there are only 5 possible cases:

\$p<v\$	\$p>v\$	\$p=v\$	operations	final bitmask	modulo 3
no	no	yes	0 \| 3	3	0
no	yes	no	0 \| -2	-2	-2
no	yes	yes	0 \| -2 \| 3	-1	-1
yes	no	no	0 \| 5	5	2
yes	no	yes	0 \| 5 \| 3	7	1

138 Aspen · Accepted Answer · 2023-11-15 23:07:40Z

6

Scala 3, 71 63 bytes

Saved 8 bytes thanks to the comment of @corvus_192

x=>x zip x.tail map{case(a,b)=>b compare a}pipe(x=>x.min+x.max)

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edited Nov 15 at 23:07

answered Nov 14 at 0:20

138 Aspen

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\$\begingroup\$ 63 bytes: x=>x zip x.tail map{case(a,b)=>b compare a}pipe(x=>x.min+x.max) \$\endgroup\$
– corvus_192
Nov 15 at 20:14

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Albert.Lang · Accepted Answer · 2023-11-13 23:45:56Z

5

Python, 55 bytes

lambda S,*s:min(x:={(S<t)-(S>(S:=t))for t in s})+max(x)

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Python 2, 53 bytes

def f(s):t=map(cmp,s[1:],s[:-1]);return min(t)+max(t)

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edited Nov 13 at 23:45

answered Nov 13 at 23:35

Albert.Lang

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alephalpha · Accepted Answer · 2023-11-14 10:09:15Z

5

Nekomata, 5 bytes

∆±uÄµ

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∆±uÄµ
∆       Delta
 ±      Sign
  u     Uniquify
   Ä    Multiply by 2
    µ   Mean

answered Nov 14 at 10:09

alephalpha

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Bubbler · Accepted Answer · 2023-11-14 23:31:01Z

5

K (ngn/k), 14 bytes

+/2#?0 1'1_-':

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A slight variation on Nick Kennedy's Jelly answer. 0 1' is from coltim's comment on another K answer.

+/2#?0 1'1_-':
         1_-':    differences
     0 1'         binary search into 0 1; negative -> -1, 0 -> 0, positive -> 1
    ?             keep unique elements
  2#              cycle the elements to length 2
+/                sum

answered Nov 14 at 23:31

Bubbler

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Phan Trọng Nhân · Accepted Answer · 2023-11-17 16:26:50Z

5

Python 2, 43 bytes

lambda s:cmp(s[::-1],s)<<len(set(s))/len(s)

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Logs:

My original answer (49 bytes):

lambda s:cmp(s[-1],s[0])*(2-(len(set(s))<len(s)))

Neil's suggestion: *(2-(len(set(s))<len(s))) -> -~(len(set(s))==len(s))
xnor's suggestion: *(2-(len(set(s))<len(s))) -> <<(len(set(s))==len(s)) ; cmp(s[-1],s[0]) -> cmp(s[::-1],s)
Albert.Lang's suggestion: *(2-(len(set(s))<len(s))) -> <<len(set(s))/len(s)

Thank for amazing suggestions!

edited Nov 17 at 16:26

answered Nov 14 at 4:02

Phan Trọng Nhân

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2

\$\begingroup\$ -~(len(set(s))==len(s)) is a byte shorter than (2-(len(set(s))<len(s))). \$\endgroup\$
– Neil
Nov 14 at 9:43
2

\$\begingroup\$ Better yet, <<(len(set(s))==len(s)) without *. Also, cmp(s[::-1],s) saves a byte \$\endgroup\$
– xnor
Nov 14 at 10:02
4

\$\begingroup\$ Even more betterer: lambda s:cmp(s[::-1],s)<<len(set(s))/len(s) \$\endgroup\$
– Albert.Lang
Nov 14 at 18:18
\$\begingroup\$ Thanks for y'all amazing suggestions. Was busy so just checked cg now. \$\endgroup\$
– Phan Trọng Nhân
Nov 17 at 16:17

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Nick Kennedy · Accepted Answer · 2023-11-14 07:36:24Z

4

R, 32 29 bytes

\(x)sum(range(sign(diff(x))))

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A function taking a vector and returning the relevant result. Based on Command Master's 05AB1E answer.

Thanks to @pajonk for saving three bytes!

edited Nov 14 at 7:36

answered Nov 14 at 0:53

Nick Kennedy

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\$\begingroup\$ -3 bytes by porting your own Jelly answer :) \$\endgroup\$
– pajonk
Nov 14 at 6:18
\$\begingroup\$ I don't know R, but it doesn't look like you need the range. \$\endgroup\$
– Shaggy
Nov 14 at 9:23
1

\$\begingroup\$ Thanks @Shaggy. You don’t for the examples used but would if the sequences were longer than 3 integers. \$\endgroup\$
– Nick Kennedy
Nov 14 at 12:57

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bstrat · Accepted Answer · 2023-11-15 07:36:31Z

4

K (ngn/k), 21 16 bytes

Port of 05AB1E answer

-5 thanks to @coltim

&/+/|/\0 1'1_-':

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           1_-': deltas
       0 1'      sign
  +/|/\          add maximum
&/               minimum

edited Nov 15 at 7:36

answered Nov 14 at 12:56

bstrat

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\$\begingroup\$ I think you can use |/\ rather than 1|/\ , since the input is going to be a list (so the max-reduce-converges will end after a single iteration). There's also the golfy 0 1'intList sign version that saves several bytes. \$\endgroup\$
– coltim
Nov 14 at 15:29

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l4m2 · Accepted Answer · 2023-11-14 02:48:37Z

3

JavaScript (Node.js), 50 bytes

a=>~!a.some(p=x=>p==(p=x))*Math.sign(a[0]-a.pop())

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Use begin and end to detect direction

answered Nov 14 at 2:48

l4m2

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Mama Fun Roll · Accepted Answer · 2023-11-14 03:30:26Z

3

sclin, 23 bytes

_"-"2%map0<=>"|/"Q + &/

Try it on scline! Port of Command Master's answer.

Explanation

Prettified:

_ \- 2%map 0<=> \|/ Q + &/

_ \- 2%map negated delta (via pairwise difference)
0<=> sign (i.e. compare to 0)
\|/ Q dup and get max
+ &/ vectorized-add and get min

answered Nov 14 at 3:30

Mama Fun Roll

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Aiden Chow · Accepted Answer · 2023-11-14 07:05:32Z

3

Desmos, 33 bytes

f(L)=D.max+D.min
D=sgn(L[2...]-L)

Port of 05AB1E.

Try It On Desmos!

Try It On Desmos! - Prettified

answered Nov 14 at 7:05

Aiden Chow

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Neil · Accepted Answer · 2023-11-14 09:41:19Z

Retina, 57 51 bytes

\d+
*
Lv`\b_+,_+
+`_,_
,
O^`
,,G`
^_
-_
/[^-]+/_`_+

Try it online! Link includes test cases. Only accepts positive integer lists, but will output -2 to 2 as required. Explanation:

\d+
*

Convert to unary.

Lv`\b_+,_+
+`_,_
,

For each overlapping pair of integers, get a substring representing the delta: _+, for negative, , for 0 and ,_+ for positive.

O^`

Group identical substrings together and sort _, first.

,,G`

Keep only one of each group, but if there is only one group, keep two of it.

^_
-_

If there was a _, then prefix a - sign.

/[^-]+/_`_+

Count the runs of _s.

Edit: Saved 6 bytes by porting my answer to Retina 0.8.2 for 61 bytes and then backporting the golfs:

\d+
$*
M!&`\b1+,1+
+`1,1
,
O^`
+`¶.+¶
¶
^1
-1
((1+)|,|¶)+
$#2

Try it online! Link includes test cases. Only accepts positive integer lists, but will output -2 to 2 as required. Explanation: Retina 0.8.2 uses $* (which produces 1s) instead of * (which produces _s) for unary, needs to use M!& instead of Lv, and doesn't have an equivalent of ,,G or _ (as a command), so I had to emulate those.

lyxal · Accepted Answer · 2023-11-14 00:40:29Z

2

Vyxal `g`, 29 bits^v2, 3.625 bytes

¯±:G+

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Bitstring:

11001100111100010001111111001

Port of the 05ab1e answer

edited Nov 14 at 0:40

answered Nov 13 at 23:28

lyxal

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Neil · Accepted Answer · 2023-11-14 01:06:38Z

2

Charcoal, 23 bytes

≔ＥΦθκ⁻›ι§θκ‹ι§θκθＩ⁺⌊θ⌈θ

Try it online! Link is to verbose version of code. Explanation: Port of @Albert.Lang's Python answer.

≔ＥΦθκ⁻›ι§θκ‹ι§θκθ

Get the signs of the deltas.

Ｉ⁺⌊θ⌈θ

Add the minimum and maximum of them.

answered Nov 14 at 1:06

Neil

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tsh · Accepted Answer · 2023-11-14 02:41:54Z

2

JavaScript (Node.js), 54 bytes

a=>a.map(n=p=o=v=>[n|=a>v,p|=a<v,o|=a==v,a=v])|p-n<<!o

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answered Nov 14 at 2:41

tsh

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Arnauld · Accepted Answer · 2023-11-14 16:05:11Z

1

C (gcc), 63 bytes

Port of my JS answer.

m,p;f(a,n)int*a;{for(m=0;p=*a++,--n;)m|=p<*a?5:p>*a?-2:3;m%=3;}

Try it online!

answered Nov 14 at 16:05

Arnauld

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Graham · Accepted Answer · 2023-11-14 17:23:16Z

1

APL+WIN, 52 bytes

Prompts for vector:

+/2 1 0×(×n)×(s=⍴v),((s<⍴v)^s>0),0=s←1+|n←+/×-2-/v←⎕

Try it online! Thanks to Dyalog Classic

answered Nov 14 at 17:23

Graham

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138 Aspen · Accepted Answer · 2023-11-15 23:32:28Z

Go, 193 183 bytes

Saved 10 bytes thanks to the comment of @corvus_192

Golfed version. Attempt this online!

func c(a,b int)int{if a<b{return 1};if a>b{return -1};return 0}
func f(n[]int)int{z:=math.MaxInt64;Z:=^z;for i:=0;i<len(n)-1;i++{r:=c(n[i],n[i+1]);if r<z{z=r};if r>Z{Z=r}};return z+Z}

Ungolfed version. Attempt This Online!

package main

import (
	"fmt"
	"math"
)

func compare(a, b int) int {
	if a < b {
		return 1
	}
	if a > b {
		return -1
	}
	return 0
}

func f(nums []int) int {
	min, max := math.MaxInt64, math.MinInt64
	for i := 0; i < len(nums)-1; i++ {
		result := compare(nums[i], nums[i+1])
		if result < min {
			min = result
		}
		if result > max {
			max = result
		}
	}
	return min + max
}

func main() {
	fmt.Println(f([]int{1, 2, 3, 5, 9}))
	fmt.Println(f([]int{1, 2, 3, 5, 5}))
	fmt.Println(f([]int{1, 1, 1, 1, 1}))
	fmt.Println(f([]int{1, 1, -3, -5, -9}))
	fmt.Println(f([]int{-1, -2, -3, -5, -9}))
}

\$\begingroup\$ -9 bytes: z:=math.MaxInt64;Z:=-~z; \$\endgroup\$
– corvus_192
Nov 15 at 20:27 — corvus_192, Nov 15 at 20:27

Stack Exchange Network

Monotone sequence beatitude

21 Answers 21

05AB1E, 8 7 6 bytes

Uiua, 11 bytes

Jelly, 6 bytes

Explanation

JavaScript (ES6), 47 bytes

Method

List of cases

Scala 3, 71 63 bytes

Python, 55 bytes

Python 2, 53 bytes

Nekomata, 5 bytes

K (ngn/k), 14 bytes

Python 2, 43 bytes

R, 32 29 bytes

K (ngn/k), 21 16 bytes

JavaScript (Node.js), 50 bytes

sclin, 23 bytes

Explanation

Desmos, 33 bytes

Retina, 57 51 bytes

Vyxal `g`, 29 bits^v2, 3.625 bytes

Charcoal, 23 bytes

JavaScript (Node.js), 54 bytes

C (gcc), 63 bytes

APL+WIN, 52 bytes

Go, 193 183 bytes

Your Answer

Not the answer you're looking for? Browse other questions tagged
code-golf
sequence
integer
or ask your own question.

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Monotone sequence beatitude

21 Answers 21

05AB1E, 8 7 6 bytes

Uiua, 11 bytes

Jelly, 6 bytes

Explanation

JavaScript (ES6), 47 bytes

Method

List of cases

Scala 3, 71 63 bytes

Python, 55 bytes

Python 2, 53 bytes

Nekomata, 5 bytes

K (ngn/k), 14 bytes

Python 2, 43 bytes

R, 32 29 bytes

K (ngn/k), 21 16 bytes

JavaScript (Node.js), 50 bytes

sclin, 23 bytes

Explanation

Desmos, 33 bytes

Retina, 57 51 bytes

Vyxal g, 29 bitsv2, 3.625 bytes

Charcoal, 23 bytes

JavaScript (Node.js), 54 bytes

C (gcc), 63 bytes

APL+WIN, 52 bytes

Go, 193 183 bytes

Your Answer

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Not the answer you're looking for? Browse other questions tagged code-golfsequenceinteger or ask your own question.

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Vyxal `g`, 29 bits^v2, 3.625 bytes

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code-golf
sequence
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or ask your own question.