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[essaysir] WEEK 02 Solutions#2681

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[essaysir] WEEK 02 Solutions#2681
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@essaysir

@essaysir essaysir commented Jun 29, 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 Jun 29, 2026

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๐Ÿ“Š essaysir ๋‹˜์˜ ํ•™์Šต ํ˜„ํ™ฉ

์ด๋ฒˆ ์ฃผ ์ œ์ถœ ๋ฌธ์ œ

๋ฌธ์ œ ๋‚œ์ด๋„ ์œ ํ˜• ๋ถ„์„
climbing-stairs Easy โœ… ์˜๋„ํ•œ ์œ ํ˜•
product-of-array-except-self Medium โš ๏ธ ์œ ํ˜• ๋ถˆ์ผ์น˜
valid-anagram Easy โœ… ์˜๋„ํ•œ ์œ ํ˜•

๋ˆ„์  ํ•™์Šต ์š”์•ฝ

  • ํ’€์ดํ•œ ๋ฌธ์ œ: 5 / 75๊ฐœ
  • ์ด๋ฒˆ ์ฃผ ์œ ํ˜• ์ผ์น˜์œจ: 67% (3๋ฌธ์ œ ์ค‘ 2๋ฌธ์ œ ์ผ์น˜)

๋ฌธ์ œ ํ’€์ด ํ˜„ํ™ฉ

์นดํ…Œ๊ณ ๋ฆฌ ์ง„ํ–‰๋„ ์™„๋ฃŒ
Heap โ– โ– โ–กโ–กโ–กโ–กโ–ก 1 / 3 (Medium 1)
Array 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)
Dynamic Programming โ– โ–กโ–กโ–กโ–กโ–กโ–ก 1 / 11 (Medium 1)
Binary โ–กโ–กโ–กโ–กโ–กโ–กโ–ก 0 / 5 โ† ์•„์ง ์‹œ์ž‘ ์•ˆ ํ•จ
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
String โ–กโ–กโ–กโ–กโ–กโ–กโ–ก 0 / 10 โ† ์•„์ง ์‹œ์ž‘ ์•ˆ ํ•จ
Tree โ–กโ–กโ–กโ–กโ–กโ–กโ–ก 0 / 14 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
1 754 116 870 $0.000084
2 793 119 912 $0.000087
3 1,267 111 1,378 $0.000108
ํ•ฉ๊ณ„ 2,814 346 3,160 $0.000279

@github-actions github-actions Bot added the java label Jun 29, 2026

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์ œ ์ƒ๊ฐ์— dfs ํ•จ์ˆ˜์— ์ ์ ˆํ•œ cache๋งŒ ์ถ”๊ฐ€ํ•ด๋„ ์‹œ๊ฐ„๋ณต์žก๋„๊ฐ€ ์—„์ฒญ๋‚˜๊ฒŒ ์ข‹์•„์งˆ๊ฒƒ ๊ฐ™๋„ค์š” ( O(N) )!

@Yiseull Yiseull self-requested a review June 29, 2026 10:46
- memo ๋ฅผ ์ด์šฉํ•œ ์‹œ๊ฐ„ ๋ณต์žก๋„ ๋‹จ์ถ•

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์˜ค ์ด์ œ ์ ์ ˆํ•œ ์‹œ๊ฐ„๋ณต์žก๋„๋„ค์š”!
์ •๋‹ต์ด ํ”ผ๋ณด๋‚˜์น˜ ์ˆ˜์—ด์ธ๊ฒƒ๊นŒ์ง€ ์•„์‹ ๋‹ค๋ฉด ๊ณต๊ฐ„๋ณต์žก๋„๋„ ํ›จ์”ฌ ์ค„์ด์‹ค์ˆ˜ ์žˆ์œผ์‹ค๊ฒƒ ๊ฐ™์•„์š”!
๊ณ ์ƒํ•˜์…จ์Šต๋‹ˆ๋‹ค.

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๐Ÿท๏ธ ์•Œ๊ณ ๋ฆฌ์ฆ˜ ํŒจํ„ด ๋ถ„์„

  • ํŒจํ„ด: Dynamic Programming, Hash Map / Hash Set
  • ์„ค๋ช…: ํ”ผ๋ณด๋‚˜์น˜ ๋ณ€ํ˜•์œผ๋กœ ์ค‘๋ณต ๋ถ€๋ถ„ ๋ฌธ์ œ๋ฅผ ํ•ด๊ฒฐํ•˜๊ธฐ ์œ„ํ•ด ๋ฉ”๋ชจ์ด์ œ์ด์…˜์„ ์‚ฌ์šฉํ•œ ๋™์  ๊ณ„ํš๋ฒ• ํŒจํ„ด์ด๋ฉฐ, ํ•ด์˜ ์ค‘๋ณต ๊ณ„์‚ฐ์„ ํ•ด์‹œ๋งต์œผ๋กœ ์ €์žฅํ•ฉ๋‹ˆ๋‹ค.

๐Ÿ“Š ์‹œ๊ฐ„/๊ณต๊ฐ„ ๋ณต์žก๋„ ๋ถ„์„

โ„น๏ธ ์ด ํŒŒ์ผ์—๋Š” 3๊ฐ€์ง€ ํ’€์ด๊ฐ€ ํฌํ•จ๋˜์–ด ์žˆ์–ด ๊ฐ๊ฐ ๋ถ„์„ํ•ฉ๋‹ˆ๋‹ค.

ํ’€์ด 1: Solution.climbStairs โ€” Time: O(n) / Space: O(n)
๋ณต์žก๋„
Time O(n)
Space O(n)

ํ”ผ๋“œ๋ฐฑ: ์ค‘๋ณต ์žฌ๊ท€๋ฅผ ๋ฉ”๋ชจ์ด์ œ์ด์…˜์œผ๋กœ ์ œ๊ฑฐํ•˜์—ฌ ๊ฐ n์— ๋Œ€ํ•ด ํ•œ ๋ฒˆ๋งŒ ๊ณ„์‚ฐํ•˜๋„๋ก ๊ตฌํ˜„ํ–ˆ์Šต๋‹ˆ๋‹ค.

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

ํ’€์ด 2: Solution.productExceptSelf โ€” Time: O(n) / Space: O(1)
๋ณต์žก๋„
Time O(n)
Space O(1)

ํ”ผ๋“œ๋ฐฑ: ํ•˜๋‚˜์˜ ๋ฐฐ์—ด๊ณผ ์ƒ์ˆ˜ ๊ณต๊ฐ„์œผ๋กœ ๊ฐ ์œ„์น˜์˜ ๊ณฑ์„ ๊ณ„์‚ฐํ•ฉ๋‹ˆ๋‹ค. ์ œ์•ฝ ์กฐ๊ฑด์— ๋”ฐ๋ผ 0์˜ ์œ„์น˜ ์ฒ˜๋ฆฌ๋„ ํฌํ•จํ•ฉ๋‹ˆ๋‹ค.

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

ํ’€์ด 3: Solution.isAnagram โ€” Time: O(n + m) / Space: O(k)
๋ณต์žก๋„
Time O(n + m)
Space O(k)

ํ”ผ๋“œ๋ฐฑ: ๋‘ ๋งต์˜ ๋นˆ๋„์ˆ˜๋ฅผ ๋น„๊ตํ•ด anagram ์—ฌ๋ถ€๋ฅผ ํŒ๋‹จํ•ฉ๋‹ˆ๋‹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: Hash Map / Hash Set, Greedy, Divide and Conquer
  • ์„ค๋ช…: ๋ฐฐ์—ด์˜ ๊ณฑ์„ ์ด์šฉํ•ด ๊ฐ ์›์†Œ๋ฅผ ์ œ์™ธํ•œ ๊ณฑ์„ ๊ตฌํ•˜๋Š” ๋ฐฉ์‹์€ ๋ถ€๋ถ„ ๋ฌธ์ œ์˜ ์ตœ์ ํ™”๋กœ ๋ณผ ์ˆ˜ ์žˆ์œผ๋ฉฐ, 0์˜ ๊ฐœ์ˆ˜์— ๋”ฐ๋ฅธ ๋ถ„๊ธฐ ๋กœ์ง์€ ๋ฌธ์ œ๋ฅผ ๋‹จ์ˆœํ™”ํ•˜๋Š” ํƒ์š•์  ์ ‘๊ทผ์ฒ˜๋Ÿผ ๋ณด์ผ ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค. ๋˜ํ•œ ์ „์ฒด ๊ณฑ๊ณผ ์ œ์ˆ˜๋กœ ๋‚˜๋ˆ„์–ด ๊ตฌํ•˜๋Š” ์•„์ด๋””์–ด๋Š” ๋ฌธ์ œ๋ฅผ ๋ถ„ํ•ดํ•ด ํ•ด๊ฒฐํ•˜๋Š” ํŒจํ„ด์œผ๋กœ ํ•ด์„๋  ์—ฌ์ง€๊ฐ€ ์žˆ์Šต๋‹ˆ๋‹ค.

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๐Ÿท๏ธ ์•Œ๊ณ ๋ฆฌ์ฆ˜ ํŒจํ„ด ๋ถ„์„

  • ํŒจํ„ด: Hash Map / Hash Set
  • ์„ค๋ช…: ๋‘ ๋ฌธ์ž์—ด์˜ ๋ฌธ์ž ๋นˆ๋„๋ฅผ ํ•ด์‹œ๋งต์œผ๋กœ ์„ธ์–ด ์„œ๋กœ ๋™์ผํ•œ์ง€ ๋น„๊ตํ•˜๋Š” ๋ฐฉ์‹์œผ๋กœ ์•„๋‚˜๊ทธ๋žจ ์—ฌ๋ถ€๋ฅผ ํŒ๋‹จํ•œ๋‹ค. ๊ฐ ๋ฌธ์ž ๋“ฑ์žฅ ํšŸ์ˆ˜๋ฅผ ๋งต์— ์ €์žฅํ•˜๊ณ , ๋‘ ๋งต์˜ ๊ฐ’์„ ๋น„๊ตํ•˜๋Š” ๊ฒƒ์ด ํ•ต์‹ฌ์ด๋‹ค.

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