Create PG_합승택시요금.java

Author: kn9012

250217/PG_합승택시요금.java

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+/**
+ * 프로그래머스 합승 택시 요금
+ * - 다익스트라!!!!
+ */
+
+import java.util.*;
+
+class Solution {
+    class Node implements Comparable<Node> {
+        int node, value;
+        
+        Node (int node, int value) {
+            this.node = node;
+            this.value = value;
+        }
+        
+        @Override
+        public int compareTo(Node o) {
+            return Integer.compare(this.value, o.value);
+        }
+    }
+    
+    List<Node> list[];
+    int[] dist;
+    int len;
+    
+    public int solution(int n, int s, int a, int b, int[][] fares) {
+        len = n;
+        
+        list = new ArrayList[n + 1];
+        for (int i = 0; i <= n; i++) {
+            list[i] = new ArrayList<>();
+        }
+        
+        for (int i = 0; i < fares.length; i++) {
+            list[fares[i][0]].add(new Node(fares[i][1], fares[i][2]));
+            list[fares[i][1]].add(new Node(fares[i][0], fares[i][2]));
+        }
+        
+        int[] together = dijkstra(s);
+        int[] aloneA = dijkstra(a);
+        int[] aloneB= dijkstra(b);
+        int cost = Integer.MAX_VALUE;
+        
+        for (int i = 1; i <= n; i++) {
+            if (together[i] == Integer.MAX_VALUE || aloneA[i] == Integer.MAX_VALUE || aloneB[i] == Integer.MAX_VALUE) continue;
+            
+            cost = Math.min(cost, together[i] + aloneA[i] + aloneB[i]);
+        }
+        
+        return cost;
+    }
+    
+    public int[] dijkstra(int s) {
+        dist = new int[len + 1];
+        Arrays.fill(dist, Integer.MAX_VALUE);
+        dist[s] = 0;
+        
+        PriorityQueue<Node> queue = new PriorityQueue<>();
+        queue.add(new Node(s, 0));
+
+        while (!queue.isEmpty()) {
+            Node cur = queue.poll();
+            int node = cur.node;
+            int value = cur.value;
+            
+            if (dist[node] < value) continue;
+            
+            for (int i = 0; i < list[node].size(); i++) {
+                int nextN = list[node].get(i).node;
+                int nextV = list[node].get(i).value;
+                
+                if (dist[nextN] > value + nextV) {
+                    queue.add(new Node(nextN, value + nextV));
+                    dist[nextN] = value + nextV;
+                }
+            }
+        }
+        
+        return dist;
+    }
+}