BOJ 1504, 프로그래머스 순위

6주차-그래프/w06-Kaya/BOJ1504.java

@@ -0,0 +1,92 @@
+import java.util.*;
+import java.io.*;
+
+class Node implements Comparable<Node> {
+    int vertex, weight;
+
+    public Node(int vertex, int weight) {
+        this.vertex = vertex;
+        this.weight = weight;
+    }
+    @Override
+    public int compareTo(Node o){
+        return weight - o.weight;
+    }
+}
+public class Main {
+    static int v, e, v1, v2;
+    static ArrayList<Node>[] list;
+    static int[] dist;
+    static boolean[] check;
+    static final int INF = 200000000;
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        v = Integer.parseInt(st.nextToken());
+        e = Integer.parseInt(st.nextToken());
+
+        list = new ArrayList[v+1];
+        for(int i=0; i<list.length; i++) {
+            list[i] = new ArrayList<>();
+        }
+        dist = new int[v+1];
+        check = new boolean[v+1];
+
+        for(int i=0; i<e; i++) {
+            st = new StringTokenizer(br.readLine());
+
+            int s = Integer.parseInt(st.nextToken());
+            int f = Integer.parseInt(st.nextToken());
+            int d = Integer.parseInt(st.nextToken());
+
+            list[s].add(new Node(f, d));
+            list[f].add(new Node(s, d));
+        }
+
+        st = new StringTokenizer(br.readLine());
+        v1 = Integer.parseInt(st.nextToken());
+        v2 = Integer.parseInt(st.nextToken());
+
+        int result1 = dijkstra(1, v1) + dijkstra(v1, v2) + dijkstra(v2, v);
+        int result2 = dijkstra(1, v2) + dijkstra(v2, v1) + dijkstra(v1, v);
+
+        int ans = 0;
+        if(result1 >= INF && result2 >= INF) {
+            ans = -1;
+        } else {
+            ans = Math.min(result1, result2);
+        }
+
+        System.out.println(ans);
+    }
+
+    public static int dijkstra(int start, int end) {
+        Arrays.fill(dist, INF);
+        Arrays.fill(check, false);
+
+        PriorityQueue<Node> q = new PriorityQueue<>();
+        q.add(new Node(start, 0));
+        dist[start] = 0;
+
+        while(!q.isEmpty()) {
+            Node curr = q.poll();
+            int currNode = curr.vertex;
+            int currWeight = curr.weight;
+
+            if(check[currNode]) continue;
+            check[currNode] = true;
+
+            for(int i=0; i<list[currNode].size(); i++) {
+                int nextNode = list[currNode].get(i).vertex;
+                int nextWeight = list[currNode].get(i).weight;
+
+                if(!check[nextNode] && dist[nextNode] > currWeight + nextWeight) {
+                    dist[nextNode] = currWeight + nextWeight;
+                    q.add(new Node(nextNode, dist[nextNode]));
+                }
+            }
+        }
+        return dist[end];
+    }
+}

6주차-그래프/w06-Kaya/순위.java

@@ -0,0 +1,32 @@
+class Solution {
+    public int solution(int n, int[][] results) {
+        int answer = 0;
+        int[][] game = new int[n+1][n+1];
+
+        for(int i=0; i<results.length; i++) {
+            int win = results[i][0];
+            int lose = results[i][1];
+            game[win][lose] = 1;
+        }
+
+        // 플로이드-와샬 알고리즘
+        for(int i=1; i<=n; i++) {
+            for(int j=1; j<=n; j++) {
+                for(int k=1; k<=n; k++) {
+                    if(game[j][i] == 1 && game[i][k] == 1) {  // k가 "j한테 진 i"한테 지면 k도 j에게 진 것임
+                        game[j][k] = 1;
+                    }
+                }
+            }
+        }
+
+        for(int i=1; i<=n; i++) {
+            int result = 0;
+            for(int j=1; j<=n; j++) {
+                if(game[i][j] == 1 || game[j][i] == 1) result++;  // i가 j에게 이겼든 졌든 어쨌거나 경기를 한 것과 마찬가지니까
+            }
+            if(result == n-1) answer++;
+        }
+        return answer;
+    }
+}