\n N\uac1c\uc758 \ub3c4\uc2dc\uac00 \uc788\uc73c\uba70, \uc774\ub4e4 \uac04\uc5d0\ub294 M\uac1c\uc758 \ub2e8\ubc29\ud5a5 \ub3c4\ub85c\uac00 \uc874\uc7ac\ud569\ub2c8\ub2e4.
\n \uac01 \ub3c4\uc2dc\ub294 1\ubd80\ud130 N\uae4c\uc9c0\uc758 \uc815\uc218\ub85c \ud45c\ud604\ub429\ub2c8\ub2e4. \ub3c4\uc2dc A\uc5d0\uc11c \ub3c4\uc2dc B\ub85c \uac00\ub294
\n \ub3c4\ub85c\uac00 \uc874\uc7ac\ud558\uba74 A\uc5d0\uc11c B\ub85c \uc774\ub3d9\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.
\n K\ub77c\ub294 \ud2b9\uc815 \uac70\ub9ac\uac00 \uc8fc\uc5b4\uc9c8 \ub54c, \uac70\ub9ac K\ub9cc\ud07c \ub5a8\uc5b4\uc838 \uc788\ub294 \ub3c4\uc2dc\ub4e4\uc744 \ubaa8\ub450 \ucc3e\ub294
\n \ud504\ub85c\uadf8\ub7a8\uc744 \uc791\uc131\ud558\uc138\uc694. \ub3d9\uc77c\ud55c \ub3c4\uc2dc\uac00 \ub450 \ubc88 \uc774\uc0c1 \ucd9c\ub825\ub418\uc9c0 \uc54a\ub3c4\ub85d \ud569\ub2c8\ub2e4.\n <\/p>\n
\n N M K\n A1 B1\n A2 B2\n ...\n Am Bm\n <\/pre>\n
\n K \uac70\ub9ac\ub9cc\ud07c \ub5a8\uc5b4\uc838 \uc788\ub294 \ub3c4\uc2dc \ubc88\ud638\ub97c \uc624\ub984\ucc28\uc21c\uc73c\ub85c \ucd9c\ub825\ud55c\ub2e4. \n \ub9cc\uc57d \uadf8\ub7f0 \ub3c4\uc2dc\uac00 \uc5c6\ub2e4\uba74 -1\uc744 \ucd9c\ub825\ud55c\ub2e4.\n <\/pre>\n\uc608\uc2dc<\/h2>\n
\uc785\ub825<\/h3>\n
\n 4 4 2\n 1 2\n 1 3\n 2 4\n 3 4\n <\/pre>\n\ucd9c\ub825<\/h3>\n
\n 4\n <\/pre>\n\ubb38\uc81c \ud480\uc774 \uc811\uadfc\ubc95<\/h2>\n
\n \uc774 \ubb38\uc81c\ub294 \uadf8\ub798\ud504 \ud0d0\uc0c9(\ud2b9\ud788 \ub108\ube44 \uc6b0\uc120 \ud0d0\uc0c9 BFS)\uc744 \ud65c\uc6a9\ud558\uc5ec \ud574\uacb0\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.
\n \uc8fc\uc5b4\uc9c4 \ub3c4\uc2dc\ub294 \ub178\ub4dc, \ub3c4\ub85c\ub294 \uac04\uc120\uc73c\ub85c \ubaa8\ub378\ub9c1\ud560 \uc218 \uc788\uc73c\uba70, \ud2b9\uc815 \uac70\ub9ac\ub97c
\n \ucc3e\uae30 \uc704\ud574 BFS\ub97c \uc218\ud589\ud558\uc5ec \uac70\ub9ac K\uc5d0 \ub3c4\ub2ec\ud558\ub294 \ub3c4\uc2dc\ub97c \ucc3e\uc2b5\ub2c8\ub2e4.\n <\/p>\nBFS \uc54c\uace0\ub9ac\uc998 \uac1c\uc694<\/h3>\n
\n BFS\ub294 \uc2dc\uc791 \ub178\ub4dc\uc5d0\uc11c\ubd80\ud130 \uc778\uc811\ud55c \ubaa8\ub4e0 \ub178\ub4dc\ub97c \ud0d0\uc0c9\ud558\uace0, \ud0d0\uc0c9\uc774 \uc644\ub8cc\ub41c \ud6c4
\n \ub2e4\uc74c \ub808\ubca8\uc758 \ub178\ub4dc\ub97c \ud0d0\uc0c9\ud558\ub294 \ubc29\uc2dd\uc73c\ub85c \uc791\ub3d9\ud569\ub2c8\ub2e4. \uc774 \ubc29\uc2dd\uc740 \ucd5c\ub2e8 \uacbd\ub85c
\n \ubb38\uc81c\uc5d0 \uc801\ud569\ud569\ub2c8\ub2e4.\n <\/p>\n\uad6c\ud604 \uc0c1\uc138<\/h2>\n
\ub2e4\uc74c\uc740 \uc2a4\uc704\ud504\ud2b8\ub85c BFS\ub97c \ud1b5\ud574 \ud2b9\uc815 \uac70\ub9ac\uc758 \ub3c4\uc2dc\ub97c \ucc3e\ub294 \ucf54\ub4dc\uc785\ub2c8\ub2e4.<\/p>\n
\n import Foundation\n\n struct City {\n var number: Int\n var distance: Int\n }\n\n func findCitiesAtDistanceN(n: Int, roads: [(Int, Int)], k: Int) -> [Int] {\n \/\/ \uc778\uc811 \ub9ac\uc2a4\ud2b8 \uc0dd\uc131\n var graph = [[Int]](repeating: [Int](), count: n + 1)\n for road in roads {\n let a = road.0\n let b = road.1\n graph[a].append(b)\n }\n\n \/\/ BFS \ucd08\uae30\ud654\n var queue = [City]()\n var distances = Array(repeating: -1, count: n + 1)\n distances[1] = 0 \/\/ \uc2dc\uc791 \ub3c4\uc2dc\ub294 1\ub85c \uac00\uc815\n queue.append(City(number: 1, distance: 0))\n\n while !queue.isEmpty {\n let current = queue.removeFirst()\n let currentDistance = current.distance\n for neighbor in graph[current.number] {\n if distances[neighbor] == -1 { \/\/ \uc544\uc9c1 \ubc29\ubb38\ud558\uc9c0 \uc54a\uc558\ub2e4\uba74\n distances[neighbor] = currentDistance + 1\n queue.append(City(number: neighbor, distance: distances[neighbor]!))\n }\n }\n }\n\n \/\/ K \uac70\ub9ac\uc758 \ub3c4\uc2dc \ucc3e\uae30\n let result = distances.enumerated().compactMap { index, distance in\n distance == k ? index : nil\n }.sorted()\n\n return result.isEmpty ? [-1] : result\n }\n\n \/\/ \uc608\uc2dc \uc785\ub825\n let roads = [(1, 2), (1, 3), (2, 4), (3, 4)]\n let result = findCitiesAtDistanceN(n: 4, roads: roads, k: 2)\n \n print(result) \/\/ Output: [4]\n <\/code><\/pre>\n\ucf54\ub4dc \uc124\uba85<\/h2>\n
\n \uc704 \ucf54\ub4dc\uc5d0\uc11c \uba3c\uc800 \uc778\uc811 \ub9ac\uc2a4\ud2b8\ub97c \uc0dd\uc131\ud569\ub2c8\ub2e4.
\n \uac01 \ub3c4\uc2dc\ub294 \uc5f0\uacb0\ub41c \ub2e4\ub978 \ub3c4\uc2dc\ub4e4\uc744 \ubc30\uc5f4 \ud615\ud0dc\ub85c \uc800\uc7a5\ud569\ub2c8\ub2e4.
\n \uadf8 \ub2e4\uc74c BFS\ub97c \uc218\ud589\ud558\uc5ec \uac01 \ub3c4\uc2dc\uc5d0 \ub300\ud55c \uac70\ub9ac\ub97c \uacc4\uc0b0\ud569\ub2c8\ub2e4.
\n \ub9c8\uc9c0\ub9c9\uc73c\ub85c \uac70\ub9ac K\uc5d0 \ud574\ub2f9\ud558\ub294 \ub3c4\uc2dc\ub97c \ucc3e\uc544 \ucd9c\ub825\ud569\ub2c8\ub2e4.\n <\/p>\n\ubcf5\uc7a1\ub3c4 \ubd84\uc11d<\/h2>\n
\n \uadf8\ub798\ud504\uc758 \ubaa8\ub4e0 \ub178\ub4dc\ub97c \ubc29\ubb38\ud558\uae30 \ub54c\ubb38\uc5d0
\n \uc2dc\uac04 \ubcf5\uc7a1\ub3c4\ub294 O(N + M)\uc785\ub2c8\ub2e4.
\n \uacf5\uac04 \ubcf5\uc7a1\ub3c4 \ub610\ud55c O(N + M)\uc785\ub2c8\ub2e4.\n <\/p>\n\uacb0\ub860<\/h2>\n
\n \uc774\ubc88 \uac15\uc88c\uc5d0\uc11c\ub294 \ud2b9\uc815 \uac70\ub9ac\uc758 \ub3c4\uc2dc\ub97c \ucc3e\ub294 \ubb38\uc81c\ub97c \ub2e4\ub904\ubcf4\uc558\uc2b5\ub2c8\ub2e4.
\n BFS\ub97c \ud1b5\ud574 \ud6a8\uc728\uc801\uc73c\ub85c \ud574\uacb0\ud560 \uc218 \uc788\uc73c\uba70,
\n \uc8fc\uc758 \uae4a\uc740 \uad6c\ud604\uc774 \ud544\uc694\ud569\ub2c8\ub2e4. \ub2e4\uc591\ud55c \uc0c1\ud669\uc5d0\uc11c \ud65c\uc6a9\ud560 \uc218 \uc788\ub294
\n \uc774 \uc54c\uace0\ub9ac\uc998\uc744 \uc775\ud788\uba74, \ubcf5\uc7a1\ud55c \uadf8\ub798\ud504\uc640 \ub3c4\ub85c \ubb38\uc81c\ub97c \ud574\uacb0\ud560 \uc218 \uc788\ub294
\n \uc88b\uc740 \ud1a0\ub300\uac00 \ub420 \uac83\uc785\ub2c8\ub2e4.\n <\/p>\n<\/body><\/p>\n","protected":false},"excerpt":{"rendered":"