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[๋ฐฑ์ค€ (BOJ) / Python] 18352๋ฒˆ: ํŠน์ • ๊ฑฐ๋ฆฌ์˜ ๋„์‹œ ์ฐพ๊ธฐ

๋ฌธ์ œ ๋งํฌ: www.acmicpc.net/problem/18352 18352๋ฒˆ: ํŠน์ • ๊ฑฐ๋ฆฌ์˜ ๋„์‹œ ์ฐพ๊ธฐ ์ฒซ์งธ ์ค„์— ๋„์‹œ์˜ ๊ฐœ์ˆ˜ N, ๋„๋กœ์˜ ๊ฐœ์ˆ˜ M, ๊ฑฐ๋ฆฌ ์ •๋ณด K, ์ถœ๋ฐœ ๋„์‹œ์˜ ๋ฒˆํ˜ธ X๊ฐ€ ์ฃผ์–ด์ง„๋‹ค. (2 ≤ N ≤ 300,000, 1 ≤ M ≤ 1,000,000, 1 ≤ K ≤ 300,000, 1 ≤ X ≤ N) ๋‘˜์งธ ์ค„๋ถ€ํ„ฐ M๊ฐœ์˜ ์ค„์— ๊ฑธ์ณ์„œ ๋‘ ๊ฐœ www.acmicpc.net ๋ฌธ์ œ ์„ค๋ช… BFS๋ฅผ ์ด์šฉํ•˜์—ฌ ๋„์‹œ๋ฅผ ๋ชจ๋‘ ๋ฐฉ๋ฌธํ•˜๋Š” ๋ฐฉ๋ฒ•์„ ์ด์šฉํ•˜์˜€๋‹ค. BFS๋ฅผ ํ•˜๋Š” ์ค‘ ๋งŒ์•ฝ ํ˜„์žฌ ๋„์‹œ์˜ ์ตœ๋‹จ ๊ฑฐ๋ฆฌ ๊ฐ’์ด k ๋ณด๋‹ค ํด ๊ฒฝ์šฐ, ์ด ๋’ค์— ๋ฐฉ๋ฌธํ•˜๋Š” ๋„์‹œ๋“ค์˜ ์ตœ๋‹จ ๊ฑฐ๋ฆฌ๋Š” ๋ชจ๋‘ k๋ณด๋‹ค ํฌ๋ฏ€๋กœ BFS๋ฅผ ์ค‘์ง€ํ•œ๋‹ค. solution ํ•จ์ˆ˜ ์„ค๋ช… ์ตœ๋‹จ ๊ฑฐ๋ฆฌ๊ฐ€ k์ธ ๋„์‹œ๋“ค์„ ๋‹ด์„ ๋ฆฌ์ŠคํŠธ answer ์ดˆ๊ธฐํ™” ์ถœ๋ฐœ ๋„์‹œ๋ฅผ ํ์— ์‚ฝ์ž…..