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[parkhojeong] WEEK 04 Solutions - #2749

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Jul 18, 2026
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[parkhojeong] WEEK 04 Solutions#2749
parkhojeong merged 9 commits into
DaleStudy:mainfrom
parkhojeong:week4

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@parkhojeong

@parkhojeong parkhojeong commented Jul 17, 2026

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๋‹ต์•ˆ ์ œ์ถœ ๋ฌธ์ œ

์ž‘์„ฑ์ž ์ฒดํฌ ๋ฆฌ์ŠคํŠธ

  • Projects์˜ ์˜ค๋ฅธ์ชฝ ๋ฒ„ํŠผ(โ–ผ)์„ ๋ˆŒ๋Ÿฌ ํ™•์žฅํ•œ ๋’ค, Week๋ฅผ ํ˜„์žฌ ์ฃผ์ฐจ๋กœ ์„ค์ •ํ•ด์ฃผ์„ธ์š”.
  • ๋ฌธ์ œ๋ฅผ ๋ชจ๋‘ ํ‘ธ์‹œ๋ฉด ํ”„๋กœ์ ํŠธ์—์„œ Status๋ฅผ In Review๋กœ ์„ค์ •ํ•ด์ฃผ์„ธ์š”.
  • ์ฝ”๋“œ ๊ฒ€ํ† ์ž 1๋ถ„ ์ด์ƒ์œผ๋กœ๋ถ€ํ„ฐ ์Šน์ธ์„ ๋ฐ›์œผ์…จ๋‹ค๋ฉด PR์„ ๋ณ‘ํ•ฉํ•ด์ฃผ์„ธ์š”.

๊ฒ€ํ† ์ž ์ฒดํฌ ๋ฆฌ์ŠคํŠธ

Important

๋ณธ์ธ ๋‹ต์•ˆ ์ œ์ถœ ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ๋‹ค๋ฅธ ๋ถ„ PR ํ•˜๋‚˜ ์ด์ƒ์„ ๋ฐ˜๋“œ์‹œ ๊ฒ€ํ† ๋ฅผ ํ•ด์ฃผ์…”์•ผ ํ•ฉ๋‹ˆ๋‹ค!

  • ๋ฐ”๋กœ ์ด์ „์— ์˜ฌ๋ผ์˜จ PR์— ๋ณธ์ธ์„ ์ฝ”๋“œ ๋ฆฌ๋ทฐ์–ด๋กœ ์ถ”๊ฐ€ํ•ด์ฃผ์„ธ์š”.
  • ๋ณธ์ธ์ด ๊ฒ€ํ† ํ•ด์•ผํ•˜๋Š” PR์˜ ๋‹ต์•ˆ ์ฝ”๋“œ์— ํ”ผ๋“œ๋ฐฑ์„ ์ฃผ์„ธ์š”.
  • ํ† ์š”์ผ ์ „๊นŒ์ง€ PR์„ ๋ณ‘ํ•ฉํ•  ์ˆ˜ ์žˆ๋„๋ก ์Šน์ธํ•ด์ฃผ์„ธ์š”.

@dalestudy

dalestudy Bot commented Jul 17, 2026

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๐Ÿ“Š parkhojeong ๋‹˜์˜ ํ•™์Šต ํ˜„ํ™ฉ

์ด๋ฒˆ ์ฃผ ์ œ์ถœ ๋ฌธ์ œ

๋ฌธ์ œ ๋‚œ์ด๋„ ์œ ํ˜• ๋ถ„์„
coin-change Medium โš ๏ธ ์œ ํ˜• ๋ถˆ์ผ์น˜
find-minimum-in-rotated-sorted-array Medium โœ… ์˜๋„ํ•œ ์œ ํ˜•
maximum-depth-of-binary-tree Easy โœ… ์˜๋„ํ•œ ์œ ํ˜•
merge-two-sorted-lists Easy โœ… ์˜๋„ํ•œ ์œ ํ˜•
word-search Medium โš ๏ธ ์œ ํ˜• ๋ถˆ์ผ์น˜

๋ˆ„์  ํ•™์Šต ์š”์•ฝ

  • ํ’€์ดํ•œ ๋ฌธ์ œ: 15 / 75๊ฐœ
  • ์ด๋ฒˆ ์ฃผ ์œ ํ˜• ์ผ์น˜์œจ: 60% (5๋ฌธ์ œ ์ค‘ 3๋ฌธ์ œ ์ผ์น˜)

๋ฌธ์ œ ํ’€์ด ํ˜„ํ™ฉ

์นดํ…Œ๊ณ ๋ฆฌ ์ง„ํ–‰๋„ ์™„๋ฃŒ
Array โ– โ– โ– โ– โ–กโ–กโ–ก 5 / 10 (Medium 3, Easy 2)
Dynamic Programming โ– โ– โ– โ–กโ–กโ–กโ–ก 4 / 11 (Easy 1, Medium 3)
Heap โ– โ– โ–กโ–กโ–กโ–กโ–ก 1 / 3 (Medium 1)
Binary โ– โ–กโ–กโ–กโ–กโ–กโ–ก 1 / 5 (Easy 1)
String โ– โ–กโ–กโ–กโ–กโ–กโ–ก 2 / 10 (Easy 2)
Graph โ– โ–กโ–กโ–กโ–กโ–กโ–ก 1 / 8 (Medium 1)
Tree โ– โ–กโ–กโ–กโ–กโ–กโ–ก 1 / 14 (Medium 1)
Interval โ–กโ–กโ–กโ–กโ–กโ–กโ–ก 0 / 5 โ† ์•„์ง ์‹œ์ž‘ ์•ˆ ํ•จ
Linked List โ–กโ–กโ–กโ–กโ–กโ–กโ–ก 0 / 6 โ† ์•„์ง ์‹œ์ž‘ ์•ˆ ํ•จ
Matrix โ–กโ–กโ–กโ–กโ–กโ–กโ–ก 0 / 4 โ† ์•„์ง ์‹œ์ž‘ ์•ˆ ํ•จ

๐Ÿค– ์ด ๋Œ“๊ธ€์€ GitHub App์„ ํ†ตํ•ด ์ž๋™์œผ๋กœ ์ž‘์„ฑ๋˜์—ˆ์Šต๋‹ˆ๋‹ค.

๐Ÿ”ข API ์‚ฌ์šฉ๋Ÿ‰ (gpt-5-nano)
์š”์ฒญ ์ž…๋ ฅ ํ† ํฐ ์ถœ๋ ฅ ํ† ํฐ ํ•ฉ๊ณ„ ๋น„์šฉ
1 1,959 268 2,227 $0.000205
2 2,105 231 2,336 $0.000198
3 2,043 210 2,253 $0.000186
4 2,045 222 2,267 $0.000191
ํ•ฉ๊ณ„ 8,152 931 9,083 $0.000780

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ํ˜น์‹œ ์Šฌ๋ผ์ด์‹ฑ์„ ์“ฐ์‹  ์ด์œ ๊ฐ€ ์žˆ์œผ์‹ค๊นŒ์š”?
์Šฌ๋ผ์ด์‹ฑ์€ ๊ทธ ํฌ๊ธฐ๋งŒํผ O(N) ์‹œ๊ฐ„๋ณต์žก๋„๋ผ ๋น ๋ฅด์ง„ ์•Š์„๊ฒƒ ๊ฐ™์•„์„œ์š”,
๋ฌธ์ž์—ด์€ immutable ํ•œ ๊ฐ์ฒด๋ผ์„œ ์ƒˆ๋กœ ๋ณต์‚ฌํ•ด์„œ ์ฃผ๋Š” ๋ฐฉ์‹์œผ๋กœ ์ž‘๋™ํ•˜์ž–์•„์š”

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์ด๊ฑฐ ํ’€์ด 1900ms ๋‚˜์˜ค๋Š”๋ฐ 0ms๊นŒ์ง€ ์ค„์ผ์ˆ˜ ์žˆ๋Š”๊ฑฐ ์•„์‹œ๋‚˜์š”? ํ•œ๋ฒˆ ์‹œ๋„ํ•ด๋ณด์‹œ๋Š”๊ฒƒ๋„ ์žฌ๋ฐŒ์œผ์‹ค๊ฑฐ์—์š”!

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๋„ˆ๋ฌด ์ž˜ ํ’€์–ด ์ฃผ์…จ๋Š”๋ฐ, ๋‹ค๋งŒ ์กฐ๊ธˆ ์•„์‰ฌ์šด์ ์€ ๋กœ์ง์ด ๋„ˆ๋ฌด ๋ณต์žกํ•ด์„œ ์ฝ”๋“œ ๊ฐ€๋…์„ฑ์ด ๋–จ์–ด์ง€๋Š”๊ฒŒ ์•„๋‹๊นŒ ์‹ถ์–ด์š”
์ฐจ๋ผ๋ฆฌ ๋”๋ฏธ ํ—ค๋“œ๋ฅผ ํ•˜๋‚˜ ์จ์„œ ํ‘ธ์‹œ๋Š”๊ฒŒ ๋” ๋‚˜์„๋“ฏ ํ•˜๋‹ค๋Š” ์ƒ๊ฐ์ด ๋“ญ๋‹ˆ๋‹ค.
์‹ค์ œ๋กœ ๋‹ค๋ฅธ ๋งํฌ๋“œ ๋ฆฌ์ŠคํŠธ ๋ฌธ์ œ๋“ค์„ ํ’€๋‹ค ๋ณด์‹œ๋ฉด ๋”๋ฏธ ํ—ค๋“œ๋ฅผ ์ผ์„๋•Œ ์ฝ”๋“œ๊ฐ€ ๊ฐ„๊ฒฐํ•ด์ง€๋Š” ๊ฒฝ์šฐ๊ฐ€ ๊ฝค ๋งŽ์ด ์žˆ์–ด์š”

@daehyun99
daehyun99 self-requested a review July 17, 2026 14:38
@parkhojeong

parkhojeong commented Jul 17, 2026

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@alphaorderly
์•ŒํŒŒ๋‹˜ ๋ฆฌ๋ทฐ ๊ฐ์‚ฌํ•ฉ๋‹ˆ๋‹ค. ์•„๊นŒ ๋‹ฌ์•„์ฃผ์‹  ๋ฆฌ๋ทฐ์— ๋Œ“๊ธ€์„ ๋‚จ๊ฒผ๋Š”๋ฐ ์ถ”๊ฐ€๋กœ ์ปค๋ฐ‹์„ ํ•˜๋‹ˆ ์ œ๊ฐ€ ๋‚จ๊ธด ์ปค๋ฉ˜ํŠธ๊ฐ€ ์‚ญ์ œ๋˜์—ˆ๊ณ  ๋Œ“๊ธ€ ๋‹ค๋Š” ์ธํ’‹์ฐฝ๋„ ์—†์–ด์ง€๋„ค์š”.

์ฃผ๋กœ ์ปค๋ฉ˜ํŠธ๋ฅผ ๋ด‡ ์ปค๋ฉ˜ํŠธ์— ๋‚จ๊ฒจ์ฃผ์‹œ๋Š” ๊ฑฐ ๊ฐ™์€๋ฐ์š”. ๋ณ„๋„ ์ปค๋ฉ˜ํŠธ๋กœ ๋‚จ๊ฒจ์ฃผ์‹œ๋ฉด ์ข‹์„ ๊ฑฐ ๊ฐ™์Šต๋‹ˆ๋‹ค. ๋‹ฌ์•„์ฃผ์…จ๋˜ ๊ฒƒ๋“ค์€ ๋ณ„๋„ ์ปค๋ฉ˜ํŠธ๋กœ ๋‹ต๋ณ€๋“œ๋ฆด๊ฒŒ์š”
image

@parkhojeong

parkhojeong commented Jul 17, 2026

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@alphaorderly

์ด๊ฑฐ ํ’€์ด 1900ms ๋‚˜์˜ค๋Š”๋ฐ 0ms๊นŒ์ง€ ์ค„์ผ์ˆ˜ ์žˆ๋Š”๊ฑฐ ์•„์‹œ๋‚˜์š”? ํ•œ๋ฒˆ ์‹œ๋„ํ•ด๋ณด์‹œ๋Š”๊ฒƒ๋„ ์žฌ๋ฐŒ์œผ์‹ค๊ฑฐ์—์š”!

c98db17 ๋กœ ์ตœ์ ํ™” ์‹œ๋„ํ•ด๋ดค์Šต๋‹ˆ๋‹ค. ์ธํ’‹ ํŒจํ„ด์— ๋”ฐ๋ฅธ ์ตœ์ ํ™”๋ž‘ ์นด์šดํ„ฐ ๊ธฐ๋ฐ˜์œผ๋กœ ๋„์ค‘์— ์ฒดํฌํ•˜๋Š” ๋ฐฉ์‹์ด ์ด ๋ฌธ์ œ์—์„  ์ ํ•ฉํ•œ ๊ฑฐ ๊ฐ™๋„ค์š”!

์•ŒํŒŒ๋‹˜ ํ‘ธ์…จ๋˜ ํ’€์ด์—๋„ ์ปค๋ฉ˜ํŠธ ํ•˜๋‚˜ ๋‚จ๊ฒจ๋†“์•˜์Šต๋‹ˆ๋‹ค :) #2737 (comment)

@DaleSeo

DaleSeo commented Jul 17, 2026

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@parkhojeong ๋‹˜, ์ฃผ์ฐจ ์„ค์ • ์ข€ ๋ถ€ํƒ๋“œ๋ฆฌ๊ฒ ์Šต๋‹ˆ๋‹ค. ์•ˆ ๊ทธ๋Ÿผ ํ†ต๊ณ„์—์„œ ๋ˆ„๋ฝ์ด ๋˜์„œ์š”.

2026-07-17 at 19 42 45

@parkhojeong

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@parkhojeong ๋‹˜, ์ฃผ์ฐจ ์„ค์ • ์ข€ ๋ถ€ํƒ๋“œ๋ฆฌ๊ฒ ์Šต๋‹ˆ๋‹ค. ์•ˆ ๊ทธ๋Ÿผ ํ†ต๊ณ„์—์„œ ๋ˆ„๋ฝ์ด ๋˜์„œ์š”.

@DaleSeo ์„ค์ •ํ–ˆ์Šต๋‹ˆ๋‹ค. ํ™•์ธ ๊ฐ์‚ฌํ•ฉ๋‹ˆ๋‹ค.

@daehyun99 daehyun99 left a comment

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์•ˆ๋…•ํ•˜์„ธ์š”.
4์ฃผ์ฐจ ๋ฆฌ๋ทฐ๋ฅผ ๋งก์€ ๊น€๋Œ€ํ˜„์ž…๋‹ˆ๋‹ค!

์ „์ฒด์ ์œผ๋กœ ์ž˜ ํ’€์–ด์ฃผ์‹  ๊ฒƒ ๊ฐ™๋„ค์š”. ๊ณ ์ƒํ•˜์…จ์Šต๋‹ˆ๋‹ค!

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backtrack๊ณผ DIRECTIONS, MARKER๋ฅผ ์‚ฌ์šฉํ•œ ํ’€์ด๊ฐ€ ์ง๊ด€์ ์œผ๋กœ ์ดํ•ด๊ฐ€ ์ž˜ ๋˜์„œ ์ข‹๋„ค์š”!

@parkhojeong parkhojeong Jul 18, 2026

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๋Œ€๋ฌธ์ž ์ผ€์ด์‹ฑ์„ ์‚ฌ์šฉํ•˜๋ฉด ๊ฐ€๋…์„ฑ์ด ๊ดœ์ฐฎ๋”๋ผ๊ตฌ์š”. ๋นˆ๋„ ๊ธฐ๋ฐ˜์œผ๋กœ ์ฒดํฌํ•˜๋Š” ๋กœ์ง์€ ์ดˆ๊ธฐ ํ•œ ๋ฒˆ๋งŒ ํ•˜๋ฉด ๋˜์„œ ์ •๋ฆฌํ•ด๋ณด์•˜์Šต๋‹ˆ๋‹ค. 994aca2

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์ด๊ฑด ์‚ฌ๋‹ด์ธ๋ฐ

[3, 1] ํ…Œ์ŠคํŠธ ์ผ€์ด์Šค์— ๋Œ€ํ•˜์—ฌ, mid_idx=1์ด ๋˜๊ณ , ์•„๋ž˜์˜ ์ฝ”๋“œ์—์„œ nums[mid_idx + 1:]๊ฐ€ nums[2:]๋กœ ๋˜์–ด์„œ ์ธ๋ฑ์Šค ์—๋Ÿฌ๊ฐ€ ๋‚  ์ค„ ์•Œ์•˜๋Š”๋ฐ, ์•ˆ๋‚˜๋Š”๊ตฐ์š”!
๋ฆฌ๋ทฐํ•  ๋•Œ๋งˆ๋‹ค ์ƒˆ๋กœ์šด ์‚ฌ์‹ค์„ ์•Œ์•„๊ฐ€๊ฒŒ ๋˜๋„ค์š”.

            else:
                nums = nums[mid_idx + 1:]

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ํŒŒ์ด์ฌ์ด range ๋„˜์–ด๊ฐ€๋Š” ๊ฒฝ์šฐ์—” ๋นˆ ๋ฐฐ์—ด๋กœ ๋˜๋Š” ๊ฒƒ์„ ์‚ฌ์šฉํ•ด๋ณด์•˜์Šต๋‹ˆ๋‹ค. ๊ทผ๋ฐ ์ด ํ’€์ด๋Š” ์Šฌ๋ผ์ด์‹ฑ์ด O(n)์˜ ๋ณต์žก๋„๋ผ ์ตœ์ ํ™” ์ง„ํ–‰ํ•ด๋ดค์Šต๋‹ˆ๋‹ค. 31ba2f4

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์ด๊ฑด ์‚ฌ๋‹ด์ธ๋ฐ

[3, 1] ํ…Œ์ŠคํŠธ ์ผ€์ด์Šค์— ๋Œ€ํ•˜์—ฌ, mid_idx=1์ด ๋˜๊ณ , ์•„๋ž˜์˜ ์ฝ”๋“œ์—์„œ nums[mid_idx + 1:]๊ฐ€ nums[2:]๋กœ ๋˜์–ด์„œ ์ธ๋ฑ์Šค ์—๋Ÿฌ๊ฐ€ ๋‚  ์ค„ ์•Œ์•˜๋Š”๋ฐ, ์•ˆ๋‚˜๋Š”๊ตฐ์š”! ๋ฆฌ๋ทฐํ•  ๋•Œ๋งˆ๋‹ค ์ƒˆ๋กœ์šด ์‚ฌ์‹ค์„ ์•Œ์•„๊ฐ€๊ฒŒ ๋˜๋„ค์š”.

        else:
            nums = nums[mid_idx + 1:]

์˜คํ˜ธ ์žฌ๋ฐŒ๋Š” ์–ธ์–ด๋„ค์š”

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sys.maxsize๋กœ ์ตœ๋Œ€๊ฐ’์„ ์„ค์ •ํ•  ์ˆ˜ ์žˆ๊ตฐ์š”!
๋งŽ์ด ๋ฐฐ์›Œ๊ฐ‘๋‹ˆ๋‹ค.

@parkhojeong

parkhojeong commented Jul 18, 2026

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@alphaorderly
์Šฌ๋ผ์ด์‹ฑ์„ ๋ฏธ์ฒ˜ ์ƒ๊ฐ ๋ชปํ–ˆ์—ˆ๋Š”๋ฐ CPython3.14 ๊ธฐ์ค€์œผ๋กœ๋Š” O(k) (k=๊ธธ์ด) ์— ํ•ด๋‹นํ•˜๋Š” ์‹œ๊ฐ„,๊ณต๊ฐ„ ๋ณต์žก๋„๋ฅผ ๊ฐ€์ง€๋„ค์š”. ์ตœ์ ํ™” ์ง„ํ–‰ํ•ด๋ดค์Šต๋‹ˆ๋‹ค! optimize find-minimum-in-rotated-sorted-array

์Šฌ๋ผ์ด์‹ฑ ๊ตฌํ˜„์ฒด ์ง„์ž…์ : _BINARY_SLICE (https://github.com/python/cpython/blob/3.14/Python/bytecodes.c#L847-L863)

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๐Ÿท๏ธ ์•Œ๊ณ ๋ฆฌ์ฆ˜ ํŒจํ„ด ๋ถ„์„

  • ํŒจํ„ด: Dynamic Programming
  • ์„ค๋ช…: ๊ธˆ์•ก๋ณ„ ์ตœ์†Œ ๋™์ „ ๊ฐœ์ˆ˜๋ฅผ ๊ตฌํ•˜๊ธฐ ์œ„ํ•ด ๊ฐ ๊ธˆ์•ก์— ๋Œ€ํ•ด ์ตœ์†Œ ๋น„์šฉ์„ ํŒ๋‹จํ•˜๋Š” DP ๋ฐฉ์‹์œผ๋กœ ๊ตฌํ˜„๋˜์–ด ์žˆ์Šต๋‹ˆ๋‹ค. ๋ถ€๋ถ„ ๋ฌธ์ œ์˜ ํ•ด๋ฅผ ์ด์šฉํ•ด ์ „์ฒด ๋ฌธ์ œ์˜ ํ•ด๋ฅผ ๊ตฌ์„ฑํ•˜๋Š” ์ „ํ˜•์ ์ธ DP ํŒจํ„ด์ž…๋‹ˆ๋‹ค.

๐Ÿ“Š ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„ ๋ถ„์„

๋ณต์žก๋„
Time O(amount * len(coins))
Space O(amount)

ํ”ผ๋“œ๋ฐฑ: ์ดˆ๊ธฐ dp ๋ฐฐ์—ด์„ 1/0์œผ๋กœ ๊ตฌ์„ฑํ•˜๋Š” ์ ‘๊ทผ์€ ๊ฐ ๊ธˆ์•ก์— ๋„๋‹ฌ ๊ฐ€๋Šฅํ•œ์ง€ ์—ฌ๋ถ€๋ฅผ ์ €์žฅํ•˜๋Š” ๋ฐฉ์‹์œผ๋กœ ์ž‘๋™ํ•œ๋‹ค. ๋‹ค๋งŒ ์ดˆ๊ธฐํ™” ๋ฐ ์—…๋ฐ์ดํŠธ ๋กœ์ง์ด ์ž˜๋ชป๋  ๊ฒฝ์šฐ ์ผ๋ถ€ ๊ฒฝ์šฐ์—์„œ -1 ์ฒ˜๋ฆฌ์™€ ๊ฒฝ๊ณ„ ์กฐ๊ฑด์ด ๋ˆ„๋ฝ๋  ์ˆ˜ ์žˆ๋‹ค.

๊ฐœ์„  ์ œ์•ˆ: ํ˜„์žฌ ๊ตฌํ˜„์ด ์ ์ ˆํ•ด ๋ณด์ž…๋‹ˆ๋‹ค.

๐Ÿ’ก ํ’€์ด์— ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„๋ฅผ ์ฃผ์„์œผ๋กœ ๋‚จ๊ฒจ๋ณด์„ธ์š”!

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๐Ÿท๏ธ ์•Œ๊ณ ๋ฆฌ์ฆ˜ ํŒจํ„ด ๋ถ„์„

  • ํŒจํ„ด: Binary Search
  • ์„ค๋ช…: ์ •๋ ฌ๋œ ๋ฐฐ์—ด์ด ํšŒ์ „๋˜์—ˆ์„ ๋•Œ ์ตœ์†Œ ์›์†Œ๋ฅผ ์ด์ง„ ํƒ์ƒ‰์œผ๋กœ ์ฐพ๋Š” ๋ฐฉ์‹์œผ๋กœ, ๊ตฌ๊ฐ„์„ ์ ˆ๋ฐ˜์œผ๋กœ ์ค„์ด๋ฉฐ ์กฐ๊ฑด์— ๋”ฐ๋ผ lo/hi๋ฅผ ์กฐ์ •ํ•ฉ๋‹ˆ๋‹ค.

๐Ÿ“Š ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„ ๋ถ„์„

๋ณต์žก๋„
Time O(log n)
Space O(1)

ํ”ผ๋“œ๋ฐฑ: ์ ์ ˆํ•œ ์ด๋ถ„ํƒ์ƒ‰ ๋กœ์ง์œผ๋กœ ํšŒ์ „ ํฌ์ธํŠธ๋ฅผ ์ฐพ๊ณ  ์žˆ๋‹ค. ๋ฃจํ”„ ๋‚ด์—์„œ ์ตœ์†Œ๊ฐ’ ๋น„๊ต ์กฐ๊ฑด์ด ๋ช…ํ™•ํ•˜๋‹ค.

๊ฐœ์„  ์ œ์•ˆ: ํ˜„์žฌ ๊ตฌํ˜„์ด ์ ์ ˆํ•ด ๋ณด์ž…๋‹ˆ๋‹ค.

๐Ÿ’ก ํ’€์ด์— ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„๋ฅผ ์ฃผ์„์œผ๋กœ ๋‚จ๊ฒจ๋ณด์„ธ์š”!

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๐Ÿท๏ธ ์•Œ๊ณ ๋ฆฌ์ฆ˜ ํŒจํ„ด ๋ถ„์„

  • ํŒจํ„ด: DFS
  • ์„ค๋ช…: ๋ฆฌํ”„๊นŒ์ง€ ํŠธ๋ฆฌ๋ฅผ ๊นŠ์ด ์šฐ์„  ํƒ์ƒ‰ํ•˜์—ฌ ๊ฐ ๊ฐ€์ง€์˜ ๊นŠ์ด๋ฅผ ์žฌ๊ท€์ ์œผ๋กœ ๊ตฌํ•˜๊ณ  ์ตœ๋Œ€ ๊นŠ์ด๋ฅผ ๋ฐ˜ํ™˜ํ•˜๋ฏ€๋กœ DFS ํŒจํ„ด์— ํ•ด๋‹นํ•ฉ๋‹ˆ๋‹ค.

๐Ÿ“Š ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„ ๋ถ„์„

๋ณต์žก๋„
Time O(n)
Space O(h)

ํ”ผ๋“œ๋ฐฑ: ํŠธ๋ฆฌ์˜ ๋ชจ๋“  ๋…ธ๋“œ๋ฅผ ๋ฐฉ๋ฌธํ•˜๋ฉฐ ๊ฐ ์žฌ๊ท€ ํ˜ธ์ถœ์ด ๊นŠ์ด๋ฅผ ์ฆ๊ฐ€์‹œํ‚ค๋Š” ์ „ํ˜•์ ์ธ DFS ๋ฐฉ์‹์ด๋‹ค.

๊ฐœ์„  ์ œ์•ˆ: ํ˜„์žฌ ๊ตฌํ˜„์ด ์ ์ ˆํ•ด ๋ณด์ž…๋‹ˆ๋‹ค.

๐Ÿ’ก ํ’€์ด์— ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„๋ฅผ ์ฃผ์„์œผ๋กœ ๋‚จ๊ฒจ๋ณด์„ธ์š”!

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๐Ÿท๏ธ ์•Œ๊ณ ๋ฆฌ์ฆ˜ ํŒจํ„ด ๋ถ„์„

  • ํŒจํ„ด: Two Pointers, Linked List
  • ์„ค๋ช…: ๋‘ ๊ฐœ์˜ ์ •๋ ฌ๋œ ์—ฐ๊ฒฐ๋ฆฌ์ŠคํŠธ๋ฅผ ํ•œ ๋ฆฌ์ŠคํŠธ๋กœ ๋ณ‘ํ•ฉํ•˜๋Š” ๊ณผ์ •์—์„œ ํฌ์ธํ„ฐ ๋‘ ๊ฐœ๋กœ ์ˆœํšŒํ•˜๋ฉฐ ๊ฐ’์„ ๋น„๊ตํ•˜์—ฌ ์ˆœ์„œ๋ฅผ ๋งž์ถ”๋Š” ํŒจํ„ด์ด๋‹ค. ๋‚จ์€ ๋ถ€๋ถ„์„ ํ•œ๊บผ๋ฒˆ์— ๋ถ™์ด๋Š” ๋ฐฉ์‹์ด ํŠน์ง•์ด๋‹ค.

๐Ÿ“Š ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„ ๋ถ„์„

๋ณต์žก๋„
Time O(n + m)
Space O(1)

ํ”ผ๋“œ๋ฐฑ: ๋ณ‘ํ•ฉ ๊ณผ์ •์ด ๋ฃจํ”„๋ฅผ ํ†ตํ•ด ์„ ํ˜•์ ์œผ๋กœ ์ง„ํ–‰๋˜๋ฉฐ ์•ˆ์ •์ ์œผ๋กœ ๋™์ž‘ํ•œ๋‹ค.

๊ฐœ์„  ์ œ์•ˆ: ํ˜„์žฌ ๊ตฌํ˜„์ด ์ ์ ˆํ•ด ๋ณด์ž…๋‹ˆ๋‹ค.

๐Ÿ’ก ํ’€์ด์— ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„๋ฅผ ์ฃผ์„์œผ๋กœ ๋‚จ๊ฒจ๋ณด์„ธ์š”!

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๐Ÿท๏ธ ์•Œ๊ณ ๋ฆฌ์ฆ˜ ํŒจํ„ด ๋ถ„์„

  • ํŒจํ„ด: Backtracking, Depth-First Search, Hash Map / Hash Set
  • ์„ค๋ช…: ๋‹จ์–ด ํƒ์ƒ‰ ๋ฌธ์ œ์—์„œ DFS๋กœ ๊ฒฉ์ž๋ฅผ ํƒ์ƒ‰ํ•˜๋ฉฐ ๊ฐ ์œ„์น˜์—์„œ ๋‹ค์Œ ๊ธ€์ž๋ฅผ ํ™•์ธํ•˜๊ณ , ๋ฐฉ๋ฌธ ํ‘œ์‹œ๋ฅผ ํ†ตํ•ด ๋ฐฑํŠธ๋ž˜ํ‚นํ•˜๋Š” ๋ฐฉ์‹์ด ํ•ต์‹ฌ์ด๋‹ค. ๋˜ํ•œ ๊ธ€์ž ๋นˆ๋„ ์ฒดํฌ๋ฅผ ์œ„ํ•œ ํ•ด์‹œ ๋งต ์‚ฌ์šฉ๋„ ํฌํ•จ๋œ๋‹ค.

๐Ÿ“Š ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„ ๋ถ„์„

๋ณต์žก๋„
Time O(N * 4^L)
Space O(L)

ํ”ผ๋“œ๋ฐฑ: ์‚ฌ์ „ ๊ฒ€์‚ฌ๋กœ ๋ฌธ์ž ๋นˆ๋„์™€ ๋ฐฉํ–ฅ ํƒ์ƒ‰์„ ์ตœ์ ํ™”ํ•˜๋ ค๊ณ  ์‹œ๋„ํ•œ๋‹ค. ๋ฐฑํŠธ๋ž˜ํ‚น ์‹œ ์ค‘๋ณต ๋ฐฉ๋ฌธ ์ œ์–ด๊ฐ€ ํ•ต์‹ฌ์ด๋‹ค.

๊ฐœ์„  ์ œ์•ˆ: ํ˜„์žฌ ๊ตฌํ˜„์ด ์ ์ ˆํ•ด ๋ณด์ž…๋‹ˆ๋‹ค.

๐Ÿ’ก ํ’€์ด์— ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„๋ฅผ ์ฃผ์„์œผ๋กœ ๋‚จ๊ฒจ๋ณด์„ธ์š”!

@parkhojeong

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์•ˆ๋…•ํ•˜์„ธ์š”. 4์ฃผ์ฐจ ๋ฆฌ๋ทฐ๋ฅผ ๋งก์€ ๊น€๋Œ€ํ˜„์ž…๋‹ˆ๋‹ค!

์ „์ฒด์ ์œผ๋กœ ์ž˜ ํ’€์–ด์ฃผ์‹  ๊ฒƒ ๊ฐ™๋„ค์š”. ๊ณ ์ƒํ•˜์…จ์Šต๋‹ˆ๋‹ค!

๋ฆฌ๋ทฐ ๊ฐ์‚ฌํ•ฉ๋‹ˆ๋‹ค. ๋Œ€ํ˜„๋‹˜ ๋ฆฌ๋ทฐ ๋‚จ๊ฒจ์ฃผ์‹  ์ดํ›„์— ๋ช‡๊ฐ€์ง€ ์ตœ์ ํ™”ํ•˜์—ฌ์„œ ์ปค๋ฉ˜ํŠธ ๋‚จ๊ฒจ๋‘์—ˆ์Šต๋‹ˆ๋‹ค

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