다익스트라만 복습 어려워 ㅠ

Basic_Of_Algorithm/src/Today_22_06_03/deliveryAgain.java

@@ -0,0 +1,84 @@
+package Today_22_06_03;
+
+public class deliveryAgain {
+
+	public static void main(String[] args) {
+
+
+		int n = 3;
+
+		int [][]road = {{1,2,1},{1,3,5},{2,3,1}};
+
+		int k = 2;
+
+		int answer = 0;
+
+		int [][] map = new int[n+1][n+1];
+
+		int INF = 500001;
+
+		for(int i=1;i<map.length;i++) {
+			for(int j = 1 ; j < map[0].length;j++) {
+				if(i==j)continue;
+				map[i][j] = INF;
+			}
+		}
+
+		for(int i = 0 ; i < road.length;i++) {
+			int a = road[i][0];
+			int b = road[i][1];
+			int value = road[i][2];
+
+			if(map[a][b] > value) {
+				map[a][b] = value;
+				map[b][a] = value;
+			}
+		}
+
+
+		int[]dist = new int[n+1];
+
+		for(int i=2 ; i<dist.length;i++) {
+			dist[i] = INF;
+		}
+
+		boolean[] visited=  new boolean[n+1];
+
+		visited[1] = true;
+
+
+		for(int i = 1 ; i < n ; i ++) {
+
+
+
+			int min_value = INF;
+			int min_idx = 1;
+
+			for(int j=2;j<=n;j++) {
+				if(!visited[j] && dist[j] < min_value) {
+					min_value = dist[j];
+					min_idx = j;
+				}
+			}
+
+			visited[min_idx] = true;
+
+
+			for(int j=2;j<=n;j++) {
+				if(dist[j] > dist[min_idx] + map[min_idx][j]) {
+					dist[j] = dist[min_idx] + map[min_idx][j];
+				}
+			}
+
+		}
+
+		for(int i = 1 ; i <dist.length;i++) {
+			if(dist[i]<=k)answer++;
+		}
+
+
+		System.out.println(answer);
+
+		for(int i : dist)System.out.print(i+",");
+	}
+}

Basic_Of_Algorithm/src/Today_22_06_03/dijikstra.java

@@ -0,0 +1,80 @@
+package Today_22_06_03;
+
+class graph{
+
+	private int n ;
+	private int maps[][];
+
+	public graph(int n) {
+		this.n = n;
+		maps = new int[n+1][n+1];
+	}
+	public void input(int i,int j,int w) {
+		maps[i][j] = w;
+		maps[j][i] = w;
+	}
+	public void dijikstra(int v) {
+		int distance[] = new int[n+1];
+		boolean[]check = new boolean[n+1];
+
+		for(int i = 1; i < n+1; i++) {
+			distance[i] = Integer.MAX_VALUE;
+		}
+		distance[v] = 0;
+		check[v] = true;
+
+		for(int i = 1; i < n+1;i++) {
+			if(!check[i] && maps[v][i] != 0) {
+				distance[i] = maps[v][i];
+			}
+		}
+
+		for(int a = 0 ; a < n-1; a++) {
+			int min = Integer.MAX_VALUE;
+			int min_idx = 1;
+
+			for(int i=1;i<n+1;i++) {
+				if(!check[i] && distance[i]!=Integer.MAX_VALUE) {
+					if(distance[i] < min) {
+						min = distance[i];
+						min_idx = i;
+					}
+				}
+			}
+			check[min_idx] = true;
+			for(int i = 1; i < n+1; i++) {
+				if(!check[i] && maps[min_idx][i]!=0) {
+					distance[i] = distance[min_idx]+maps[min_idx][i];
+				}
+			}
+		}
+		for(int i =1 ;i<n+1;i++) {
+			System.out.print(distance[i]+" ");
+		}
+		System.out.println((" "));
+	}
+
+}
+
+public class dijikstra {
+
+	public static void main(String[] args) {
+
+		graph g = new graph(8);
+
+		g.input(1, 2, 3);
+		g.input(1, 5, 4);
+		g.input(1, 4, 4);
+		g.input(2, 3, 2);
+		g.input(3, 4, 1);
+		g.input(4, 5, 2);
+		g.input(5, 6, 4); 
+		g.input(4, 7, 6);
+		g.input(7, 6, 3);
+		g.input(3, 8, 3);
+		g.input(6, 8, 2);
+		g.dijikstra(1);
+
+
+	}
+}