\uc774\ubc88 \ud3ec\uc2a4\ud2b8\uc5d0\uc11c\ub294 \ub2e4\uc775\uc2a4\ud2b8\ub77c \uc54c\uace0\ub9ac\uc998\uc5d0 \ub300\ud574 \uc54c\uc544\ubcf4\uace0, \uc774\ub97c \ud65c\uc6a9\ud55c \ubb38\uc81c\ub97c \ud480\uc5b4\ubcf4\ub3c4\ub85d \ud558\uaca0\uc2b5\ub2c8\ub2e4. \ub2e4\uc775\uc2a4\ud2b8\ub77c \uc54c\uace0\ub9ac\uc998\uc740 \uadf8\ub798\ud504\uc758 \uac01 \uc815\uc810 \uac04\uc758 \ucd5c\ub2e8 \uacbd\ub85c\ub97c \uad6c\ud558\ub294 \uc54c\uace0\ub9ac\uc998\uc73c\ub85c, \uc8fc\ub85c \ub2e4\uc591\ud55c \uacbd\ub85c \ud0d0\uc0c9 \ubb38\uc81c\uc5d0 \uc0ac\uc6a9\ub429\ub2c8\ub2e4.<\/p>\n
\ub2e4\uc775\uc2a4\ud2b8\ub77c \uc54c\uace0\ub9ac\uc998\uc740 \uac00\uc911\uce58\uac00 \uc788\ub294 \uadf8\ub798\ud504\uc5d0\uc11c \uc2dc\uc791 \uc815\uc810\uc73c\ub85c\ubd80\ud130 \ub2e4\ub978 \ubaa8\ub4e0 \uc815\uc810\uae4c\uc9c0\uc758 \ucd5c\ub2e8 \uacbd\ub85c\ub97c \ucc3e\ub294 \ud6a8\uc728\uc801\uc778 \ubc29\ubc95\uc785\ub2c8\ub2e4. \uc774 \uc54c\uace0\ub9ac\uc998\uc740 \ud2b9\uc815 \uc815\uc810\uc5d0 \ub3c4\ub2ec\ud560 \ub54c\uae4c\uc9c0\uc758 \uacbd\ub85c \uae38\uc774\ub97c \uacc4\uc0b0\ud558\uace0, \ucd5c\ub2e8 \uacbd\ub85c\ub97c \uc9c0\uc18d\uc801\uc73c\ub85c \uc5c5\ub370\uc774\ud2b8\ud558\ub294 \ubc29\uc2dd\uc73c\ub85c \uc791\ub3d9\ud569\ub2c8\ub2e4.<\/p>\n
\uc8fc\uc5b4\uc9c4 \uac00\uc911\uce58 \uadf8\ub798\ud504\uc5d0\uc11c \uc2dc\uc791 \uc815\uc810\uacfc \ub3c4\ucc29 \uc815\uc810 \uc0ac\uc774\uc758 \ucd5c\ub2e8 \uacbd\ub85c\ub97c \uad6c\ud558\ub294 \ubb38\uc81c\uc785\ub2c8\ub2e4. \uadf8\ub798\ud504\ub294 \uc815\uc810\uc758 \uc218\uc640 \uac04\uc120\uc758 \uc218\uac00 \uc8fc\uc5b4\uc9c0\uace0, \uac01 \uac04\uc120\uc758 \uac00\uc911\uce58\ub3c4 \ud568\uaed8 \uc81c\uacf5\ub429\ub2c8\ub2e4.<\/p>\n
\uc2dc\uc791 \uc815\uc810 S\uc5d0\uc11c \ub3c4\ucc29 \uc815\uc810 E\uae4c\uc9c0\uc758 \ucd5c\ub2e8 \uacbd\ub85c \uae38\uc774\ub97c \ucd9c\ub825\ud569\ub2c8\ub2e4. \ub9cc\uc57d \ub3c4\ub2ec\ud560 \uc218 \uc5c6\ub2e4\uba74 -1\uc744 \ucd9c\ub825\ud569\ub2c8\ub2e4.<\/p>\n
import java.util.*;\n\npublic class Dijkstra {\n static class Edge {\n int to;\n int weight;\n Edge(int to, int weight) {\n this.to = to;\n this.weight = weight;\n }\n }\n\n public static void main(String[] args) {\n Scanner scanner = new Scanner(System.in);\n \n \/\/ \uadf8\ub798\ud504 \uad6c\uc131\n int N = scanner.nextInt(); \/\/ \uc815\uc810 \uc218\n int M = scanner.nextInt(); \/\/ \uac04\uc120 \uc218\n int S = scanner.nextInt(); \/\/ \uc2dc\uc791 \uc815\uc810\n int E = scanner.nextInt(); \/\/ \ub3c4\ucc29 \uc815\uc810\n\n List[] graph = new ArrayList[N + 1];\n for (int i = 1; i <= N; i++) {\n graph[i] = new ArrayList<>();\n }\n\n \/\/ \uac04\uc120 \uc785\ub825 \ubc1b\uae30\n for (int i = 0; i < M; i++) {\n int A = scanner.nextInt();\n int B = scanner.nextInt();\n int W = scanner.nextInt();\n graph[A].add(new Edge(B, W));\n graph[B].add(new Edge(A, W)); \/\/ \ubb34\ud5a5 \uadf8\ub798\ud504\n }\n\n \/\/ \ub2e4\uc775\uc2a4\ud2b8\ub77c \uc54c\uace0\ub9ac\uc998 \uc2e4\ud589\n int result = dijkstra(graph, N, S, E);\n System.out.println(result);\n }\n\n public static int dijkstra(List[] graph, int N, int start, int end) {\n int[] dist = new int[N + 1];\n Arrays.fill(dist, Integer.MAX_VALUE);\n dist[start] = 0;\n\n PriorityQueue pq = new PriorityQueue<>(Comparator.comparingInt(e -> e.weight));\n pq.offer(new Edge(start, 0));\n\n boolean[] visited = new boolean[N + 1];\n\n while (!pq.isEmpty()) {\n Edge current = pq.poll();\n int currentNode = current.to;\n\n if (visited[currentNode]) continue;\n visited[currentNode] = true;\n\n for (Edge edge : graph[currentNode]) {\n if (visited[edge.to]) continue;\n\n if (dist[currentNode] + edge.weight < dist[edge.to]) {\n dist[edge.to] = dist[currentNode] + edge.weight;\n pq.offer(new Edge(edge.to, dist[edge.to]));\n }\n }\n }\n\n return dist[end] == Integer.MAX_VALUE ? -1 : dist[end];\n }\n}<\/edge><\/edge><\/edge><\/code><\/pre>\n3.2. \ucf54\ub4dc \uc124\uba85<\/h3>\n
\uc704 \ucf54\ub4dc\ub294 Java\ub85c \uc791\uc131\ub41c \ub2e4\uc775\uc2a4\ud2b8\ub77c \uc54c\uace0\ub9ac\uc998\uc758 \uad6c\ud604\uc785\ub2c8\ub2e4. \ub2e4\uc74c\uc740 \uc8fc\uc694 \ubd80\ubd84\uc5d0 \ub300\ud55c \uc124\uba85\uc785\ub2c8\ub2e4:<\/p>\n
\n- Edge \ud074\ub798\uc2a4:<\/strong> \uadf8\ub798\ud504\uc758 \uac04\uc120\uc744 \uc815\uc758\ud558\ub294 \ud074\ub798\uc2a4\uc785\ub2c8\ub2e4. \uac01 \uac04\uc120\uc740 \ubaa9\uc801\uc9c0 \ub178\ub4dc\uc640 \uac00\uc911\uce58\ub97c \uac00\uc9c0\uace0 \uc788\uc2b5\ub2c8\ub2e4.<\/li>\n
- \uadf8\ub798\ud504 \ucd08\uae30\ud654:<\/strong> \uc778\uc811 \ub9ac\uc2a4\ud2b8 \ubc29\uc2dd\uc73c\ub85c \uadf8\ub798\ud504\ub97c \ucd08\uae30\ud654\ud569\ub2c8\ub2e4.<\/li>\n
- \uc6b0\uc120\uc21c\uc704 \ud050:<\/strong> \ud604\uc7ac \ucd5c\ub2e8 \uacbd\ub85c\ub97c \ud0d0\uc0c9\ud558\uae30 \uc704\ud574 \uc0ac\uc6a9\ub429\ub2c8\ub2e4. \ub354 \uc9e7\uc740 \uac70\ub9ac\uc758 \ub178\ub4dc\ub97c \uc6b0\uc120\uc801\uc73c\ub85c \ucc98\ub9ac\ud569\ub2c8\ub2e4.<\/li>\n
- \ub2e4\uc775\uc2a4\ud2b8\ub77c \uc54c\uace0\ub9ac\uc998:<\/strong> \ub9e4 \ubc18\ubcf5\uc5d0\uc11c \uac00\uc7a5 \uc791\uc740 \uac70\ub9ac\ub97c \uac00\uc9c4 \ub178\ub4dc\ub97c \uc120\ud0dd\ud558\uace0 \ud574\ub2f9 \ub178\ub4dc\uc5d0 \uc5f0\uacb0\ub41c \ub178\ub4dc\ub4e4\uc758 \uac70\ub9ac\ub97c \uc5c5\ub370\uc774\ud2b8\ud569\ub2c8\ub2e4.<\/li>\n<\/ul>\n
4. \uc2dc\uac04 \ubcf5\uc7a1\ub3c4<\/h2>\n
\ub2e4\uc775\uc2a4\ud2b8\ub77c \uc54c\uace0\ub9ac\uc998\uc758 \uc2dc\uac04 \ubcf5\uc7a1\ub3c4\ub294 \uc6b0\uc120\uc21c\uc704 \ud050\uc758 \uc0ac\uc6a9 \uc5ec\ubd80\uc5d0 \ub530\ub77c \ub2ec\ub77c\uc9d1\ub2c8\ub2e4. \ubc30\uc5f4\uc744 \uc6b0\uc120\uc21c\uc704 \ud050\ub85c \uc0ac\uc6a9\ud560 \uacbd\uc6b0 O((N + M) log N)\uc785\ub2c8\ub2e4. \uc5ec\uae30\uc11c N\uc740 \uc815\uc810\uc758 \uc218, M\uc740 \uac04\uc120\uc758 \uc218\uc785\ub2c8\ub2e4. \uc774 \uc54c\uace0\ub9ac\uc998\uc740 \uc801\uc740 \uac04\uc120 \uc218\uc5d0 \ube44\ud574 \uc815\uc810\uc774 \ub9ce\uc740 \uadf8\ub798\ud504\uc5d0\uc11c \uc88b\uc740 \uc131\ub2a5\uc744 \ubcf4\uc785\ub2c8\ub2e4.<\/p>\n
5. \ub9c8\ubb34\ub9ac<\/h2>\n
\uc774\ubc88 \ud3ec\uc2a4\ud2b8\uc5d0\uc11c\ub294 \ub2e4\uc775\uc2a4\ud2b8\ub77c \uc54c\uace0\ub9ac\uc998\uc744 \uc774\uc6a9\ud55c \ucd5c\ub2e8 \uacbd\ub85c \ubb38\uc81c\ub97c \ud574\uacb0\ud558\ub294 \ubc29\ubc95\uc5d0 \ub300\ud574 \uc54c\uc544\ubcf4\uc558\uc2b5\ub2c8\ub2e4. \uc774 \uc54c\uace0\ub9ac\uc998\uc740 \ub2e4\uc591\ud55c \ubd84\uc57c\uc5d0\uc11c \ud65c\uc6a9\ub420 \uc218 \uc788\uc73c\uba70, \ud2b9\ud788 \ub124\ud2b8\uc6cc\ud06c, \uc9c0\ub3c4 \uc11c\ube44\uc2a4, \ucd5c\uc801\ud654 \ubb38\uc81c\uc5d0\uc11c \ub9ce\uc774 \uc0ac\uc6a9\ub429\ub2c8\ub2e4. \ucf54\ub529 \ud14c\uc2a4\ud2b8\uc5d0\uc11c \uc774\ub7ec\ud55c \uc54c\uace0\ub9ac\uc998\uc5d0 \ub300\ud55c \uc774\ud574\uc640 \ubb38\uc81c \ud574\uacb0 \ub2a5\ub825\uc740 \ub9e4\uc6b0 \uc911\uc694\ud558\ub2c8, \uc5f0\uc2b5\uc744 \uafb8\uc900\ud788 \ud558\uc2dc\ub294 \uac83\uc744 \ucd94\ucc9c\ub4dc\ub9bd\ub2c8\ub2e4.<\/p>\n
<\/body><\/p>\n","protected":false},"excerpt":{"rendered":"