Look & Say Sequence Going from Left to Right in a number, take a digit and insert how many times this digit appears to the left of the digit. . If a digit has already appeared, that needs to be skipped succeedingly. You need to generate 4 numbers in the sequence. Ex. 655 Number1: Starting Number: 655 – 6 appears 1 time and 5 appears two times = 1625 Number2: Starting Number: 1625 – 1 appears 1 time, 6 appears 1 time, 2 appears 1 time, 5 appears 1 time = 11161215 Number3: Starting Number = 11161215 – 1 appears 5 times, 6 appears 1 time, 2 appears 1 time, 5 appears 1 time = 51161215 Numbeer4: Starting Number = 51161215 – 5 appears two times, 1 appears 4 times, 6 appears 1 time and 2 appear 1 time = 25411612
📌 Challenge Details and Links
ExcelBI Excel Challenge Number: 444
Challenge Difficulty: ⭐️⭐️
📥Download Sample File
📥Link to the solutions on LinkedIn
Solving the challenge of Generate Look-and-Say Sequence with Power Query
Power Query solution 1 for Generate Look-and-Say Sequence, proposed by Aditya Kumar Darak 🇮🇳:
let
Source = Excel.CurrentWorkbook(){[Name = "data"]}[Content],
Return = Table.AddColumn(
Source,
"Answer",
each [
G = List.Generate(
() => [a = 0, b = Text.From([Numbers])],
(f) => f[a] <= 4,
(f) => [
a = f[a] + 1,
L = List.Distinct(Text.ToList(f[b])),
T = List.Transform(L, (x) => Text.From(Text.Length(Text.Select(f[b], x))) & x),
b = Text.Combine(T)
],
(f) => f[b]
),
S = List.Skip(G),
C = Text.Combine(S, ", ")
][C]
)
in
ReturnPower Query solution 2 for Generate Look-and-Say Sequence, proposed by Ramiro Ayala Chávez:
let
S = Excel.CurrentWorkbook(){[Name = "Table1"]}[Content],
Sol = Table.AddColumn(
S,
"Answer Expected",
each
let
a = [Numbers],
T = Table.FromColumns,
L = Text.ToList,
F = Text.From,
G = Table.Group,
C = Table.RowCount,
Z = List.Zip,
TC = Text.Combine,
LC = List.Combine,
LT = List.Transform,
b = G(T({L(F(a))}), {"Column1"}, {"G", each C(_)}),
c = Z({b[G], b[Column1]}),
d = TC(LC(LT(c, each LT(_, F)))),
e = G(T({L(F(d))}), {"Column1"}, {"G", each C(_)}),
f = Z({e[G], e[Column1]}),
g = TC(LC(LT(f, each LT(_, F)))),
h = G(T({L(F(g))}), {"Column1"}, {"G", each C(_)}),
i = Z({h[G], h[Column1]}),
j = TC(LC(LT(i, each LT(_, F)))),
k = G(T({L(F(j))}), {"Column1"}, {"G", each C(_)}),
l = Z({k[G], k[Column1]}),
m = TC(LC(LT(l, each LT(_, F)))),
n = d & ", " & g & ", " & j & ", " & m
in
n
)
in
SolSolving the challenge of Generate Look-and-Say Sequence with Excel
Excel solution 1 for Generate Look-and-Say Sequence, proposed by Bo Rydobon 🇹🇭:
=MAP(
A2:A10,
LAMBDA(
x,
ARRAYTOTEXT(
SCAN(
x,
{1,
2,
3,
4},
LAMBDA(
n,
v,
LET(
m,
MID(
n,
SEQUENCE(
LEN(
n
)
),
1
),
CONCAT(
SORTBY(
DROP(
GROUPBY(
HSTACK(
XMATCH(
m,
m
),
m
),
m,
ROWS,
0,
0
),
,
1
),
{2,
1}
)
)
)
)
)
)
)
)Excel solution 2 for Generate Look-and-Say Sequence, proposed by Rick Rothstein:
=MAP(
A2:A10,
LAMBDA(
r,
ARRAYTOTEXT(
SCAN(
r,
{1,
2,
3,
4},
LAMBDA(
a,
x,
LET(
u,
UNIQUE(
MID(
a,
SEQUENCE(
LEN(
a
)
),
1
)
),
CONCAT(
LEN(
a
)-LEN(
SUBSTITUTE(
a,
u,
""
)
)&u
)
)
)
)
)
)
)Excel solution 3 for Generate Look-and-Say Sequence, proposed by John V.:
=MAP(
A2:A10,
LAMBDA(
x,
ARRAYTOTEXT(
SCAN(
x,
ROW(
1:4
),
LAMBDA(
a,
v,
LET(
i,
MID(
a,
SEQUENCE(
LEN(
a
)
),
1
),
u,
TOROW(
UNIQUE(
i
)
),
CONCAT(
BYCOL(
N(
i=u
),
SUM
)&u
)
)
)
)
)
)
)Excel solution 4 for Generate Look-and-Say Sequence, proposed by محمد حلمي:
=MAP(
A2:A10,
LAMBDA(
a,
ARRAYTOTEXT(
SCAN(
a,
SEQUENCE(
4
),
LAMBDA(
a,
v,
LET(
e,
MID(
a,
SEQUENCE(
LEN(
a
)
),
1
),
x,
UNIQUE(
e
),
CONCAT(
MAP(
x,
LAMBDA(
n,
SUM(
N(
n=e
)
)
)
)&x
)
)
)
)
)
)
)Excel solution 5 for Generate Look-and-Say Sequence, proposed by Kris Jaganah:
=MAP(A2:A10,
LAMBDA(w,
ARRAYTOTEXT(SCAN(w,
SEQUENCE(
4
),
LAMBDA(y,
z,
LET(a,
MID(
y,
SEQUENCE(
LEN(
y
)
),
1
),
CONCAT(MAP(UNIQUE(
a
),
LAMBDA(x,
SUM(--(a=x))&x)))))))))Excel solution 6 for Generate Look-and-Say Sequence, proposed by Julian Poeltl:
=MAP(
A2:A10,
LAMBDA(
Nu,
LET(
C,
LAMBDA(
N,
LET(
SP,
MID(
N,
SEQUENCE(
LEN(
N
)
),
1
),
U,
UNIQUE(
SP
),
Co,
MAP(
U,
LAMBDA(
A,
COUNTA(
FILTER(
SP,
SP=A
)
)
)
),
CONCAT(
Co&U
)
)
),
TEXTJOIN(
", ",
,
C(
Nu
),
C(
C(
Nu
)
),
C(
C(
C(
Nu
)
)
),
C(
C(
C(
C(
Nu
)
)
)
)
)
)
)
)Excel solution 7 for Generate Look-and-Say Sequence, proposed by Timothée BLIOT:
=MAP(A2:A10,
LAMBDA(z,
ARRAYTOTEXT(SCAN(z,
{1;1;1;1},
LAMBDA(a,
v,
LET(B,
MID(
a,
SEQUENCE(
LEN(
a
)
),
1
),
CONCAT(MAP(UNIQUE(
B
),
LAMBDA(x,
SUM(--(x=B))&x)))))))))Excel solution 8 for Generate Look-and-Say Sequence, proposed by Oscar Mendez Roca Farell:
=MAP(
A2:A10,
LAMBDA(
a,
ARRAYTOTEXT(
SCAN(
a,
ROW(
1:4
),
LAMBDA(
i,
x,
LET(
m,
--MID(
i,
SEQUENCE(
LEN(
i
)
),
1
),
f,
FREQUENCY(
m,
m
),
CONCAT(
IFS(
f,
HSTACK(
f,
m
),
1,
""
)
)
)
)
)
)
)
)
Or alternatively:
=MAP(
A2:A10,
LAMBDA(
a,
LET(
F,
LAMBDA(
j,
LET(
m,
MID(
j,
SEQUENCE(
LEN(
j
)
),
1
),
REDUCE(
"",
UNIQUE(
m
),
LAMBDA(
i,
x,
i&SUM(
N(
m=x
)
)&x
)
)
)
),
ARRAYTOTEXT(
SCAN(
a,
ROW(
1:4
),
LAMBDA(
i,
x,
F(
i
)
)
)
)
)
)
)Excel solution 9 for Generate Look-and-Say Sequence, proposed by Sunny Baggu:
=MAP(
A2:A10,
LAMBDA(
t,
ARRAYTOTEXT(
SCAN(
t,
SEQUENCE(
4
),
LAMBDA(
a,
v,
LET(
_m,
MID(
a,
SEQUENCE(
LEN(
a
)
),
1
),
_u,
UNIQUE(
_m
),
_c,
MAP(
_u,
LAMBDA(
a,
SUM(
N(
_m = a
)
)
)
),
CONCAT(
_c & _u
)
)
)
)
)
)
)Excel solution 10 for Generate Look-and-Say Sequence, proposed by LEONARD OCHEA 🇷🇴:
=MAP(
A2:A10,
LAMBDA(
x,
ARRAYTOTEXT(
SCAN(
x,
SEQUENCE(
4
),
LAMBDA(
a,
b,
LET(
m,
MID(
a,
SEQUENCE(
LEN(
a
)
),
1
),
& u,
UNIQUE(
m
),
CONCAT(
BYROW(
N(
u=TOROW(
m
)
),
SUM
)&u
)
)
)
)
)
)
)Excel solution 11 for Generate Look-and-Say Sequence, proposed by Diarmuid Early:
=MAP(A2:A10,
LAMBDA(in,
ARRAYTOTEXT(SCAN(in,
SEQUENCE(
4
),
LAMBDA(a,
v,
LET(digits,
MID(
a,
SEQUENCE(
LEN(
a
)
),
1
),
digUni,
UNIQUE(
digits
),
digCnt,
BYROW(--(digUni=TOROW(
digits
)),
SUM),
CONCAT(
HSTACK(
digCnt,
digUni
)
)))))))
The idea:
* digits lists the digits from the previous number
* digUni is the unique digits (in the order they appear)
* digCnt is the count of each unique digit
* The CONCAT combines the counts and digits in order to form the next number
* SCAN runs that operation 4 times (starting from the input)
* ARRAYTOTEXT merges those 4 numbers into a comma-separated list
* MAP applies that whole operation to each starting number
I tried a GROUPBY solution first,
but I had to wrap it in 2 SORTBYs (to switch the column order and to have the digits in order of appearance instead of ascending order)Excel solution 12 for Generate Look-and-Say Sequence, proposed by Burhan Cesur:
=MAP(A2:A10,
LAMBDA(x,
TEXTJOIN(", ",
,
SCAN(x,
SEQUENCE(
4
),
LAMBDA(s,
v,
LET(c,
s,
a,
MID(
c,
SEQUENCE(
LEN(
c
)
),
1
),
CONCAT(TOROW(HSTACK(BYROW(1*(UNIQUE(
a
)=TRANSPOSE(
a
)),
SUM),
UNIQUE(
a
))))))))))Excel solution 13 for Generate Look-and-Say Sequence, proposed by Tyler Cameron:
=LET(z,
LAMBDA(u,
LET(a,
MID(
u,
SEQUENCE(
LEN(
u
)
),
1
),
CONCAT(MAP(UNIQUE(
a
),
LAMBDA(x,
SUM(--(x=a))&x))))),
MAP(
A2:A10,
LAMBDA(
x,
LET(
l,
z(
x
),
m,
z(
l
),
n,
z(
m
),
o,
z(
n
),
TEXTJOIN(
", ",
,
l,
m,
n,
o
)
)
)
))Excel solution 14 for Generate Look-and-Say Sequence, proposed by Talia Cao, CPA:
=MAP(A2:A10, LAMBDA(n, ARRAYTOTEXT(
SCAN(n, SEQUENCE(4), LAMBDA(a, v,
LET(Chrs, MID(a, SEQUENCE(LEN(a)), 1),
Uniq, TRANSPOSE(UNIQUE(Chrs)),
Ct, BYCOL(--(Uniq=Chrs), LAMBDA(c, SUM(c))),
CONCAT(Ct & Uniq)
))))))Solving the challenge of Generate Look-and-Say Sequence with Python
Python solution 1 for Generate Look-and-Say Sequence, proposed by Konrad Gryczan, PhD:
import pandas as pd
input = pd.read_excel("443 Look and Say Sequence.xlsx", usecols="A", nrows=10)
test = pd.read_excel("443 Look and Say Sequence.xlsx", usecols="B", nrows=10)
def generate_next(number):
number_str = str(number)
digits = []
for digit in number_str:
if digit not in digits:
digits.append(digit)
result = ""
for digit in digits:
count = number_str.count(digit)
result += str(count) + digit
return int(result)
def generate_sequence(start_digit, iter=4):
result = [start_digit]
for i in range(iter):
next_number = generate_next(result[-1])
result.append(next_number)
all_numbers = [str(num) for num in result if num != start_digit]
return ", ".join(all_numbers)
result = input.copy()
result["Answer Expected"] = result["Numbers"].map(lambda x: generate_sequence(x))
print(result["Answer Expected"].equals(test["Answer Expected"])) # True
Solving the challenge of Generate Look-and-Say Sequence with Python in Excel
Python in Excel solution 1 for Generate Look-and-Say Sequence, proposed by Abdallah Ally:
import pandas as pd
file_path = 'Excel_Challenge_443 - Look and Say Sequence.xlsx'
df = pd.read_excel(file_path)
# Perform data transformation and cleansing
def look_say_sequence(col):
number = str(col)
numbers = []
for i in range(4):
digits = ''
for num in number:
if num not in digits:
digits += num
numbers.append(''.join([str(number.count(x)) + x for x in digits]))
number = numbers[-1]
return ', '.join(numbers)
df['My Answer'] = df['Numbers'].apply(look_say_sequence)
df['Check'] = df['Answer Expected'] == df['My Answer']
df
Python in Excel solution 2 for Generate Look-and-Say Sequence, proposed by ferhat CK:
al2 = xl("A1:A10", headers=True)
ansEx = []
for j in al2.Numbers:
y = []
x = str(j)
for _ in range(4):
v = np.array(list(x))
indexes = np.unique(v, return_index=True)[1]
x = "".join([str((v == v[index]).sum()) + v[index] for index in sorted(indexes)])
y.append(x)
ansEx.append(", ".join(y))
pd.DataFrame({"Answer Expected": ansEx})
Solving the challenge of Generate Look-and-Say Sequence with R
R solution 1 for Generate Look-and-Say Sequence, proposed by Konrad Gryczan, PhD:
library(tidyverse)
library(readxl)
input = read_excel("Excel/443 Look and Say Sequence.xlsx", range = "A1:A10")
test = read_excel("Excel/443 Look and Say Sequence.xlsx", range = "B1:B10")
generate_next = function(number) {
number_str = as.character(number)
digits = str_split(number_str, "")[[1]]
unique_digits = unique(digits)
result = map_chr(unique_digits, function(digit) {
count = sum(digits == digit)
paste0(count, digit)
}) %>% paste0(collapse = "")
as.numeric(result)
}
generate_sequence = function(start_digit, iter = 4) {
result = start_digit
for (i in 1:iter) {
next_number = generate_next(result[length(result)])
result = c(result, next_number)
}
all = result %>%
setdiff(., start_digit) %>%
paste0(collapse = ", ")
return(all)
}
result = input %>%
mutate(`Answer Expected` = map_chr(Numbers, generate_sequence))
R solution 2 for Generate Look-and-Say Sequence, proposed by Anil Kumar Goyal:
library(tidyverse)
data.frame(
Numbers = c(1, 8, 41)
) %>%
mutate(`Answer Expected` = map_chr(Numbers, .f = (.a) {
accumulate(1:4, ~ .x %>%
str_split("") %>%
unlist() %>%
{table(.)[unique(.)]} %>%
tibble::enframe() %>%
{c(rbind(.$value, .$name))} %>%
str_c(collapse = ""),
.init = .a)[-1] %>%
unlist() %>%
str_c(collapse = ", ")
}))
&&