[20250827] BOJ / G3 / ACM Craft / 김민진

Author: zinnnn37

zinnnn37/202508/26 BOJ G1 동전 뒤집기.md

@@ -35,14 +35,17 @@ public class BJ_1285_동전_뒤집기 {
     }
 
     private static void sol() throws IOException {
-        // 행 뒤집기
+        // 뒤집는 경우의 수(열)
         for (int rowFillped = 0; rowFillped < (1 << N); rowFillped++) {
             // 뒷면
             int totalTails = 0;
 
             for (int row = 0; row < N; row++) {
                 // 0일 때 뒤집지 않고(0), 1일 때 뒤집을 때(1) 0이 되어야 해서 XOR 연산
+                // 여기서 열 뒤집기
                 int tailsInCol = Integer.bitCount(coins[row] ^ rowFillped);
+                
+                // 행은 직접적으로 뒤집지 않고 뒷면의 개수를 비교해서 확인
                 totalTails += Math.min(tailsInCol, N - tailsInCol);
             }
             ans = Math.min(ans, totalTails);

zinnnn37/202508/27 BOJ G3 ACM Craft.md

@@ -0,0 +1,89 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class BJ_1005_ACM_Craft {
+
+	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;
+	private static int   K;
+	private static int   W;
+	private static int[] dp;
+	private static int[] time;
+	private static int[] inDegree;
+
+	private static Queue<Integer>  q;
+	private static List<Integer>[] graph;
+
+	public static void main(String[] args) throws IOException {
+		int T = Integer.parseInt(br.readLine());
+
+		while (T-- > 0) {
+			init();
+			sol();
+		}
+		bw.write(sb.toString());
+		bw.flush();
+		bw.close();
+		br.close();
+	}
+
+	private static void init() throws IOException {
+		st = new StringTokenizer(br.readLine());
+		N  = Integer.parseInt(st.nextToken());
+		K  = Integer.parseInt(st.nextToken());
+
+		dp   = new int[N + 1];
+		time = new int[N + 1];
+		st   = new StringTokenizer(br.readLine());
+		for (int i = 1; i <= N; i++) {
+			time[i] = Integer.parseInt(st.nextToken());
+		}
+
+		graph = new ArrayList[N + 1];
+		for (int i = 1; i <= N; i++) {
+			graph[i] = new ArrayList<>();
+		}
+
+		inDegree = new int[N + 1];
+		for (int i = 1; i <= K; i++) {
+			st = new StringTokenizer(br.readLine());
+			int u = Integer.parseInt(st.nextToken());
+			int v = Integer.parseInt(st.nextToken());
+
+			graph[u].add(v);
+			inDegree[v]++;
+		}
+
+		W = Integer.parseInt(br.readLine());
+		q = new ArrayDeque<>();
+	}
+
+	private static void sol() throws IOException {
+		for (int i = 1; i <= N; i++) {
+			// 시작 건물
+			if (inDegree[i] == 0) {
+				dp[i] = time[i];
+				q.offer(i);
+			}
+		}
+
+		while (!q.isEmpty()) {
+			int cur = q.poll();
+
+			for (int nxt : graph[cur]) {
+				dp[nxt] = Math.max(dp[nxt], dp[cur] + time[nxt]);
+				if (--inDegree[nxt] == 0) {
+					q.offer(nxt);
+				}
+			}
+		}
+		sb.append(dp[W]).append("\n");
+	}
+
+}
+```