[20250415] BOJ / P5 / 개미 / 신희을

Author: ShinHeeEul

ShinHeeEul/202504/15 BOJ P5 개미.md

@@ -0,0 +1,127 @@
+```java
+import java.util.*;
+
+public class Main {
+
+	static int N;
+	static int logN;
+	static Node[][] parents;
+	
+	static int[] ants;
+	
+	static ArrayList<Node>[] lists;
+	
+	public static void main(String[] args) throws Exception {
+    	
+		N = read();
+    	
+		ants = new int[N + 1];
+		logN = (int) (Math.log(N) / Math.log(2));
+		
+		lists = new ArrayList[N + 1];
+		
+		
+		parents = new Node[N + 1][logN + 1];
+		for(int i = 1; i <= N; i++) {
+			lists[i] = new ArrayList<>();
+			ants[i] = read();
+		}
+		
+		
+		for(int i = 1; i < N; i++) {
+			int a = read();
+			int b = read();
+			int c = read();
+			
+			lists[a].add(new Node(b, c));
+			lists[b].add(new Node(a, c));
+		}
+
+		dfs(1, 0);
+		parents[1][0] = new Node(0,0);
+//		for(int i = 1; i <= N; i++) {
+//			System.out.println(parents[i][0].index);
+//		}
+
+		for(int i = 1; i <= logN; i++) {
+			for(int j = 1; j <= N; j++) {
+				Node parent = parents[j][i-1];
+				if(parent == null) continue;
+				
+				Node node = parents[parent.index][i-1];
+				
+				if(node == null) continue;
+				
+				parents[j][i] = new Node(node.index, parent.value + node.value);
+			}
+		}
+		
+		
+		StringBuilder sb = new StringBuilder();
+		for(int i = 1; i <= N; i++) {
+			int ant = ants[i];
+			int room = i;
+			for(int j = logN; j >= 0; j--) {
+				if(parents[room][j] == null) continue;
+				
+				if(parents[room][j].value > ant) continue;
+				
+				ant -= parents[room][j].value;
+				room = parents[room][j].index;
+				
+			}
+			
+			sb.append(room == 0 ? 1 : room).append("\n");
+		}
+		
+		System.out.println(sb);
+		
+		
+    }
+	
+	public static void dfs(int node, int parent) {
+		
+		for(Node n : lists[node]) {
+			if(n.index == parent) continue;
+			parents[n.index][0] = new Node(node, n.value);
+			dfs(n.index, node);
+		}
+		
+	}
+	
+	private static class Node {
+		int index;
+		int value;
+		
+		public Node(int parent, int value) {
+			this.index = parent;
+			this.value = value;
+		}
+	}
+    
+    
+    
+    private static int read() throws Exception {
+	    int c;
+	    int n = 0;
+	    boolean negative = false;
+
+	    while ((c = System.in.read()) <= 32) {
+	        if (c == -1) return -1;
+	    }
+
+	    if (c == '-') {
+	        negative = true;
+	        c = System.in.read();
+	    }
+
+	    do {
+	        n = n * 10 + (c - '0');
+	        c = System.in.read();
+	    } while (c > 32);
+
+	    return negative ? -n : n;
+	}
+}
+
+```