[20251201] BOJ / G5 / 최소비용 구하기 / 강신지

ksinji/202512/01 BOJ 최소비용 구하기.md

@@ -0,0 +1,78 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static class City implements Comparable<City> {
+        int number;
+        int cost;
+
+        City(int number, int cost) {
+            this.number = number;
+            this.cost = cost;
+        }
+
+        @Override
+        public int compareTo(City other) {
+            return Integer.compare(this.cost, other.cost);
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+
+        int n = Integer.parseInt(br.readLine());
+        int m = Integer.parseInt(br.readLine()); 
+
+        List<City>[] graph = new ArrayList[n + 1];
+        for (int i = 1; i <= n; i++) {
+            graph[i] = new ArrayList<>();
+        }
+
+        for (int i = 0; i < m; i++) {
+            st = new StringTokenizer(br.readLine());
+            int from = Integer.parseInt(st.nextToken());
+            int to   = Integer.parseInt(st.nextToken());
+            int cost = Integer.parseInt(st.nextToken());
+
+            graph[from].add(new City(to, cost));
+        }
+
+        st = new StringTokenizer(br.readLine());
+        int start = Integer.parseInt(st.nextToken());
+        int end   = Integer.parseInt(st.nextToken());
+
+        int[] dist = new int[n + 1];
+        boolean[] visited = new boolean[n + 1];
+        Arrays.fill(dist, Integer.MAX_VALUE);
+        dist[start] = 0;
+
+        PriorityQueue<City> pq = new PriorityQueue<>();
+        pq.offer(new City(start, 0));
+
+        while (!pq.isEmpty()) {
+            City cur = pq.poll();
+            int now = cur.number;
+            int costSoFar = cur.cost;
+
+            if (visited[now]) continue;
+            visited[now] = true;
+
+            for (City next : graph[now]) {
+                int nextCity = next.number;
+                int nextCost = costSoFar + next.cost;
+
+                if (!visited[nextCity] && dist[nextCity] > nextCost) {
+                    dist[nextCity] = nextCost;
+                    pq.offer(new City(nextCity, nextCost));
+                }
+            }
+        }
+
+        System.out.println(dist[end]);
+    }
+}
+
+```