07 그래프

06_mst/shin/1197.cpp

@@ -0,0 +1,70 @@
+#include<iostream>
+#include<vector>
+#include<tuple>
+#include<algorithm>
+
+using namespace std;
+
+int v, e;
+vector<tuple<int, int, int>> edges; // (가중치, 정점1, 정점2)
+vector<tuple<int, int, int>> tree;	// mst
+int parent[10001];
+
+int find_root(int x) {
+	if (parent[x] == x)
+		return x;
+	return parent[x] = find_root(parent[x]);	// 경로 압축
+}
+
+void union_root(int v1, int v2) {	// 서로 다른 두 집합 연결
+	v1 = find_root(v1);
+	v2 = find_root(v2);
+
+	if (v1 != v2)
+		parent[v2] = v1;	// 두 집합 연결(union)
+}
+
+int main() {
+	ios::sync_with_stdio(false);
+	cin.tie(NULL);
+	cout.tie(NULL);
+
+	cin >> v >> e;
+
+	int a, b, c;
+	for (int i = 0; i < e; i++) {
+		cin >> a >> b >> c;
+		edges.push_back({ c,a,b });
+	}
+	sort(edges.begin(), edges.end());
+
+	for (int i = 1; i <= v; i++) {
+		parent[i] = i;
+	}
+
+	for (int i = 0; i < e; i++) {
+		// 간선 뽑아내기
+		auto [w, v1, v2] = edges[i];
+
+		// 사이클이 존재하는지 확인
+		if (find_root(v1) == find_root(v2))	continue;
+
+		// 사이클이 발생하지 않으면, mst에 현재 간선을 추가
+		tree.push_back(edges[i]);
+
+		// Parent 관계 갱신
+		union_root(v1, v2);
+
+		// 만약 정점 개수 v에 대해 v-1개의 간선을 찾았다면 종료
+		if (tree.size() == v - 1)	break;
+	}
+
+	int ans = 0;
+	for (int i = 0; i < tree.size(); i++) {
+		int w = get<0>(tree[i]);
+		ans += w;
+	}
+	cout << ans;
+
+	return 0;
+}

06_mst/shin/16398.java

@@ -0,0 +1,90 @@
+import java.io.*;
+import java.util.*;
+
+public class BJ16398 {
+	static int n;
+	static int[][] map;
+	static StringTokenizer st;
+	static int[] parent;
+
+	static class Edge{
+		int v1, v2, w;
+
+		Edge(int v1, int v2, int w){
+			this.v1 = v1;
+			this.v2 =v2;
+			this.w = w;
+		}
+
+//		public int compareTo(Edge e) {
+//		}
+	}
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		n = Integer.parseInt(br.readLine());
+
+		map = new int[n+1][n+1];
+		for(int i=0 ; i<n ; i++) {
+			st = new StringTokenizer(br.readLine());
+			for(int j=0 ; j<n ; j++) {
+				map[i][j] = Integer.parseInt(st.nextToken());
+			}
+		}
+
+		parent = new int[n+1];
+		for(int i=1 ; i<=n ; i++) {
+			parent[i] = i;
+		}
+
+		// 간선리스트 추출
+		List<Edge> edges = new ArrayList<>();
+		for(int i=0 ; i<n ; i++) {
+			for(int j=i+1 ; j<n ; j++) {
+				if(map[i][j] != 0)
+					edges.add(new Edge(i,j,map[i][j]));
+			}
+		}
+
+		// 오름차순 정렬
+		edges.sort((a,b)-> a.w - b.w);
+
+		List<Edge> tree = new ArrayList<>();
+
+		for(int i=0 ; i<edges.size(); i++) {
+			int v1 = edges.get(i).v1;
+			int v2 = edges.get(i).v2;
+			int w = edges.get(i).w;
+
+			if(find_root(v1) == find_root(v2))
+				continue;
+
+			tree.add(new Edge(v1,v2,w));
+			union(v1,v2);
+
+			if(tree.size() == n-1)
+				break;
+		}
+
+		long total = 0;
+		for(Edge e : tree) {
+			total += e.w;
+		}
+		System.out.println(total);
+
+	}
+
+	static int find_root(int v) {
+		if(parent[v] == v)
+			return v;
+		return parent[v] = find_root(parent[v]);
+	}
+
+	static void union(int v1, int v2) {
+	    int root1 = find_root(v1);
+	    int root2 = find_root(v2);
+	    // 루트끼리 병합
+	    if (root1 != root2)
+	        parent[root2] = root1;
+	}
+}

06_mst/shin/1647.java

@@ -0,0 +1,75 @@
+import java.io.*;
+import java.util.*;
+
+public class BJ1647 {
+
+	static class Edge{
+		int v1, v2, w;
+
+		Edge(int v1, int v2, int w){
+			this.v1 = v1;
+			this.v2 =v2;
+			this.w = w;
+		}
+
+//		public int compareTo(Edge e) {
+//		}
+	}
+	static int n,m;
+	static int[] parent;
+	static ArrayList<Edge> edges;
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		StringTokenizer st = new StringTokenizer(br.readLine());
+
+		int n = Integer.parseInt(st.nextToken());
+		int m = Integer.parseInt(st.nextToken());
+
+		edges = new ArrayList<>();
+		for(int i=0 ; i<m ; i++) {
+			st = new StringTokenizer(br.readLine());
+			int v1 = Integer.parseInt(st.nextToken());
+			int v2 = Integer.parseInt(st.nextToken());
+			int w = Integer.parseInt(st.nextToken());
+
+			edges.add(new Edge(v1, v2, w));
+		}
+
+		edges.sort((a,b)->a.w - b.w);
+
+		parent = new int[n+1];
+		for (int i = 1; i <= n; i++) {
+			parent[i] = i;
+		}
+
+		long total = 0;
+		int maxW = 0;
+		for(int i=0 ; i<edges.size(); i++) {
+			Edge edge = edges.get(i);
+
+			// 사이클이 아닌경우
+			if(find_root(edge.v1) != find_root(edge.v2)){
+				total += edge.w;
+				union(edge.v1, edge.v2);
+				maxW = edge.w;
+			}
+		}
+
+		System.out.println(total - maxW);
+	}
+
+	static int find_root(int x) {
+		if(parent[x] == x)	return x;
+		return parent[x] = find_root(parent[x]);
+	}
+
+	static void union(int x, int y) {
+		int root_x = find_root(x);
+		int root_y = find_root(y);
+
+		if(root_x != root_y) {
+			parent[root_y] = root_x;	// 루트끼리의 병합
+		}
+	}
+}

07_graph/shin/10026.cpp

@@ -0,0 +1,89 @@
+#include <iostream>
+#include <queue>
+#include <vector>
+
+using namespace std;
+int n;
+
+char map[101][101];
+bool isVisited[101][101];
+bool isVisited2[101][101];
+int cnt, cnt2;	// cnt : 적록색약이 아닌 사람이 봤을때의 구역의 개수 ,cnt2 : // 적록색약인 사람이 봤을때의 구역의 개수
+int dx[4] = { -1,1,0,0 };
+int dy[4] = { 0,0,-1,1 };
+
+// 적록색약이 아닌 사람이 봤을때의 구역 파악하기
+void bfs(int x, int y) {
+	isVisited[x][y] = true;
+	queue<pair<int, int>> q;
+	q.push({ x,y });
+	char color = map[x][y];
+	while (!q.empty()) {
+		int topx = q.front().first;
+		int topy = q.front().second;
+		q.pop();
+		for (int i = 0; i < 4; i++) {
+			int nx = topx + dx[i];
+			int ny = topy + dy[i];
+			if (nx < 0 || nx >= n || ny < 0 || ny >= n)
+				continue;
+			if (!isVisited[nx][ny] && map[nx][ny] == color) {
+				q.push({ nx,ny });
+				isVisited[nx][ny] = true;
+			}
+		}
+	}
+}
+// 적록색약인 사람이 봤을때의 구역 파악하기
+void bfs2(int x, int y) {
+	isVisited2[x][y] = true;
+	queue<pair<int, int>> q;
+	q.push({ x,y });
+	char color = map[x][y];
+	while (!q.empty()) {
+		int topx = q.front().first;
+		int topy = q.front().second;
+		q.pop();
+		for (int i = 0; i < 4; i++) {
+			int nx = topx + dx[i];
+			int ny = topy + dy[i];
+			if (nx < 0 || nx >= n || ny < 0 || ny >= n)
+				continue;
+			if (!isVisited2[nx][ny] && (map[nx][ny] == color ||
+				map[nx][ny] == 'R' && color == 'G' || map[nx][ny] == 'G' && color == 'R')) {
+				q.push({ nx,ny });
+				isVisited2[nx][ny] = true;
+			}
+		}
+	}
+}
+
+int main()
+{
+	ios_base::sync_with_stdio(false);
+	cin.tie(NULL);
+	cout.tie(NULL);
+
+	cin >> n;
+	for (int i = 0; i < n; i++) {
+		for (int j = 0; j < n; j++) {
+			cin >> map[i][j];
+		}
+	}
+	for (int i = 0; i < n; i++) {
+		for (int j = 0; j < n; j++) {
+			if (!isVisited[i][j]) {
+				bfs(i, j);
+				cnt++;
+			}
+			if (!isVisited2[i][j]) {
+				bfs2(i, j);
+				cnt2++;
+			}
+		}
+	}
+
+	cout <<cnt << " " << cnt2;
+
+	return 0;
+}