From 8ded16e30bc7ad0b786ddd6c766fcf068c1e2b52 Mon Sep 17 00:00:00 2001
From: zinnnn37 <zinnnn37@gmail.com>
Date: Sun, 19 Oct 2025 21:52:17 +0900
Subject: [PATCH] =?UTF-8?q?[20251019]=20BOJ=20/=20P3=20/=20=EA=B5=90?=
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---
 ...0 \354\225\212\353\212\224\353\213\244.md" | 93 +++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 "zinnnn37/202510/19 BOJ P3 \352\265\220\354\210\230\353\213\230\354\235\200 \352\270\260\353\213\244\353\246\254\354\247\200 \354\225\212\353\212\224\353\213\244.md"

diff --git "a/zinnnn37/202510/19 BOJ P3 \352\265\220\354\210\230\353\213\230\354\235\200 \352\270\260\353\213\244\353\246\254\354\247\200 \354\225\212\353\212\224\353\213\244.md" "b/zinnnn37/202510/19 BOJ P3 \352\265\220\354\210\230\353\213\230\354\235\200 \352\270\260\353\213\244\353\246\254\354\247\200 \354\225\212\353\212\224\353\213\244.md"
new file mode 100644
index 00000000..6d23ab14
--- /dev/null
+++ "b/zinnnn37/202510/19 BOJ P3 \352\265\220\354\210\230\353\213\230\354\235\200 \352\270\260\353\213\244\353\246\254\354\247\200 \354\225\212\353\212\224\353\213\244.md"	
@@ -0,0 +1,93 @@
+```java
+import java.io.*;
+import java.util.StringTokenizer;
+
+public class BJ_3830_교수님은_기다리지_않는다 {
+
+	private static final BufferedReader  br = new BufferedReader(new InputStreamReader(System.in));
+	private static final BufferedWriter  bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	private static final StringBuilder   sb = new StringBuilder();
+	private static       StringTokenizer st;
+
+	private static int N, M;
+	private static int[] parent, weight;
+
+	public static void main(String[] args) throws IOException {
+		while (init()) {
+			sol();
+		}
+		bw.flush();
+		bw.close();
+		br.close();
+	}
+
+	private static boolean init() throws IOException {
+		st = new StringTokenizer(br.readLine());
+		N = Integer.parseInt(st.nextToken());
+		M = Integer.parseInt(st.nextToken());
+
+		if (N == 0) return false;
+
+		parent = new int[N + 1];
+		weight = new int[N + 1];
+		for (int i = 1; i <= N; i++) {
+			parent[i] = i;
+		}
+
+		return true;
+	}
+
+	private static void sol() throws IOException {
+		while (M-- > 0) {
+			st = new StringTokenizer(br.readLine());
+
+			String cmd = st.nextToken();
+
+			if (cmd.equals("!")) {
+				int a = Integer.parseInt(st.nextToken());
+				int b = Integer.parseInt(st.nextToken());
+				int w = Integer.parseInt(st.nextToken());
+
+				union(a, b, w);
+			} else if (cmd.equals("?")) {
+				int a = Integer.parseInt(st.nextToken());
+				int b = Integer.parseInt(st.nextToken());
+
+				if (find(a) == find(b)) {
+					bw.write(weight[b] - weight[a] + "\n");
+				} else {
+					bw.write("UNKNOWN\n");
+				}
+			}
+		}
+	}
+
+	private static int find(int a) {
+		if (a == parent[a]) return a;
+
+		int root = find(parent[a]);
+		weight[a] += weight[parent[a]];
+		parent[a] = root;
+
+		return root;
+	}
+
+	private static void union(int a, int b, int w) {
+		int rootA = find(a);
+		int rootB = find(b);
+
+		if (rootA == rootB) {
+			return;
+		}
+
+		if (rootA < rootB) {
+			parent[rootB] = rootA;
+			weight[rootB] = weight[a] - weight[b] + w;
+		} else {
+			parent[rootA] = rootB;
+			weight[rootA] = weight[b] - weight[a] - w;
+		}
+	}
+
+}
+```
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