JavaCote · KangBaekGwa · Jan 20, 2026
diff --git a/week38/강성욱/baekjoon/NQueen.java b/week38/강성욱/baekjoon/NQueen.java
@@ -0,0 +1,67 @@
+package week38.강성욱.baekjoon;
+
+import java.util.Arrays;
+
+/**
+ * PackageName : week38.강성욱.baekjoon
+ * FileName    : NQueen
+ * Author      : Baekgwa
+ * Date        : 26. 1. 20.
+ * Description : 
+ * =====================================================================================================================
+ * DATE          AUTHOR               NOTE
+ * ---------------------------------------------------------------------------------------------------------------------
+ * 26. 1. 20.     Baekgwa               Initial creation
+ */
+public class NQueen {
+	class Solution {
+
+		private static int count = 0;
+
+		public int solution(int n) {
+			boolean[][] map = new boolean[n][n];
+
+			for (int i = 0; i < n; i++) {
+				Arrays.fill(map[i], true);
+			}
+
+			dfs(0, n, map);
+			return count;
+		}
+
+		private void dfs(int y, int n, boolean[][] map) {
+			if(y == n) {
+				count++;
+				return;
+			}
+
+			for(int x = 0; x < n; x++) {
+				if(!map[y][x]) continue;
+
+				boolean[][] nextMap = new boolean[n][n];
+				for (int i = 0; i < n; i++) {
+					nextMap[i] = map[i].clone();
+				}
+
+				updateMap(nextMap, x, y, n);
+				dfs(y + 1, n, nextMap);
+			}
+		}
+
+		private void updateMap(boolean[][] map, int x, int y, int n) {
+			for (int ny = y + 1; ny < n; ny++) {
+				map[ny][x] = false;
+
+				int diff = ny - y;
+
+				if (x - diff >= 0) {
+					map[ny][x - diff] = false;
+				}
+
+				if (x + diff < n) {
+					map[ny][x + diff] = false;
+				}
+			}
+		}
+	}
+}
diff --git a/week38/강성욱/baekjoon/입국심사.java b/week38/강성욱/baekjoon/입국심사.java
@@ -0,0 +1,70 @@
+package week38.강성욱.baekjoon;
+
+/**
+ * PackageName : week38.강성욱.baekjoon
+ * FileName    : 입국심사
+ * Author      : Baekgwa
+ * Date        : 26. 1. 20.
+ * Description : 
+ * =====================================================================================================================
+ * DATE          AUTHOR               NOTE
+ * ---------------------------------------------------------------------------------------------------------------------
+ * 26. 1. 20.     Baekgwa               Initial creation
+ */
+public class 입국심사 {
+	class Solution {
+		// 그럼 심사원의 명수는 times size 만큼이네?
+		// 그냥 비어있는곳에 갓다 넣어버리면 그게 더 이득인가?
+		// 꼭 그렇진 않음.
+		// 즉, 지금 비어있는 곳 중, 가장 빨리 입국심사 패스하는 사람한테 할당해줘야 젤 빨리 끝남.
+		// ----
+		// 근데 입국심사 기다리는 사람이 벌써 10억명임.
+		// 즉, 하나씩 iter 돌면 거의 반드시 터짐.
+		// 줄여야함.
+		// ---
+		// 그래서 이분탐색을 쓰면 되는거구나
+		// n 초 중에서, 얼만큼 처리할 수 있는지 확인
+		// 최소초는 음 그냥 0으로 두고
+		// 맥스는 반드시 모두 처리할 수 있는 시간, 즉, n * 1,000,000,000분(분은 솔직히 max 찾는게 낫긴한데, 그냥 이렇게 써도 큰문제는 없지않아?), 걍 max 찾자
+		public long solution(int n, int[] times) {
+			long result = Long.MAX_VALUE; //모든 사람을 처리할 수 있는 시간
+
+			long max = 0L;
+			for(int time : times) {
+				max = Math.max(time, max);
+			}
+
+			long left = 0L;
+			long right = max * n;
+
+			while(left <= right) {
+				long mid = (left + right) / 2;
+
+				long nowCount = calcPassCount(mid, times); //현재 mid(시간) 값으로, 몇명이나 처리 가능한지 확인하기
+
+				// 처리 가능하면?
+				if(nowCount >= n) {
+					right = mid - 1L;
+					result = Math.min(mid, result);
+					continue;
+				} else {
+					left = mid + 1L;
+					continue;
+				}
+			}
+
+			return result;
+		}
+
+		//현재 mid(시간) 값으로, 몇명이나 처리 가능한지 확인하기
+		private long calcPassCount(long mid, int[] times) {
+			long count = 0L;
+
+			for(int time : times) {
+				count += mid / (long) time;
+			}
+
+			return count;
+		}
+	}
+}
diff --git a/week38/강성욱/baekjoon/타임머신.java b/week38/강성욱/baekjoon/타임머신.java
@@ -0,0 +1,102 @@
+package week38.강성욱.baekjoon;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.StringTokenizer;
+
+/**
+ * PackageName : week38.강성욱.baekjoon
+ * FileName    : 타임머신
+ * Author      : Baekgwa
+ * Date        : 26. 1. 20.
+ * Description : 
+ * =====================================================================================================================
+ * DATE          AUTHOR               NOTE
+ * ---------------------------------------------------------------------------------------------------------------------
+ * 26. 1. 20.     Baekgwa               Initial creation
+ */
+public class 타임머신 {
+	public class Main {
+		// 무조건 1번 도시에서 시작!
+		// 아 음수가 있네.
+		// 이러면 다익스트라 사용 불가능
+		// 벨만 포드로
+		public static void main(String[] args) throws Exception {
+			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());
+
+			long[] dist = new long[N + 1];
+			Arrays.fill(dist, Long.MAX_VALUE);
+			dist[1] = 0;
+
+			List<Edge> edgeList = new ArrayList<>();
+			for (int i = 0; i < M; i++) {
+				st = new StringTokenizer(br.readLine());
+				int start = Integer.parseInt(st.nextToken());
+				int end = Integer.parseInt(st.nextToken());
+				int weight = Integer.parseInt(st.nextToken());
+				edgeList.add(new Edge(start, end, weight));
+			}
+
+			// N-1번까지는 최단거리 갱신, N번째는 음수 사이클 확인
+			for (int i = 0; i < N; i++) {
+				for (Edge edge : edgeList) {
+					if (dist[edge.getStart()] == Long.MAX_VALUE)
+						continue;
+
+					int start = edge.getStart();
+					int end = edge.getEnd();
+					int weight = edge.getWeight();
+
+					long distance = dist[start] + weight;
+					if (dist[end] > distance) {
+						dist[end] = distance;
+						if (i == N - 1) {
+							System.out.println("-1");
+							return;
+						}
+					}
+				}
+			}
+
+			StringBuilder sb = new StringBuilder();
+			for (int i = 2; i <= N; i++) {
+				if (dist[i] == Long.MAX_VALUE) {
+					sb.append("-1").append("\n");
+				} else {
+					sb.append(dist[i]).append("\n");
+				}
+			}
+			System.out.print(sb.toString());
+		}
+
+		private static class Edge {
+			private int start;
+			private int end;
+			private int weight;
+
+			public Edge(int start, int end, int weight) {
+				this.start = start;
+				this.end = end;
+				this.weight = weight;
+			}
+
+			public int getStart() {
+				return start;
+			}
+
+			public int getEnd() {
+				return end;
+			}
+
+			public int getWeight() {
+				return weight;
+			}
+		}
+	}
+}
diff --git a/week38/강성욱/baekjoon/파일_합치기.java b/week38/강성욱/baekjoon/파일_합치기.java
@@ -0,0 +1,61 @@
+package week38.강성욱.baekjoon;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+/**
+ * PackageName : week38.강성욱.baekjoon
+ * FileName    : 파일_합치기
+ * Author      : Baekgwa
+ * Date        : 26. 1. 20.
+ * Description : 
+ * =====================================================================================================================
+ * DATE          AUTHOR               NOTE
+ * ---------------------------------------------------------------------------------------------------------------------
+ * 26. 1. 20.     Baekgwa               Initial creation
+ */
+public class 파일_합치기 {
+	public class Main {
+		public static void main(String[] args) throws Exception {
+			BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+			StringBuilder sb = new StringBuilder();
+			int testCase = Integer.parseInt(br.readLine());
+
+			while(testCase-- > 0) {
+				int K = Integer.parseInt(br.readLine());
+				int[][] dp = new int[K+1][K+1];
+				int[] map = new int[K+1];
+
+				StringTokenizer st = new StringTokenizer(br.readLine());
+				for(int i = 1; i <= K; i++) {
+					map[i] = Integer.parseInt(st.nextToken());
+				}
+
+				int[] prefix = new int[K+1];
+				for (int i = 1; i <= K; i++) {
+					prefix[i] = prefix[i-1] + map[i];
+				}
+
+				for(int length=2; length <= K; length++) {
+					for(int start=1; start + length -1 <= K; start++) {
+						int end = start + length - 1;
+						dp[start][end] = Integer.MAX_VALUE;
+
+						for(int k=start; k<end; k++) {
+							dp[start][end] = Math.min(
+								dp[start][end],
+								dp[start][k] + dp[k+1][end] + (prefix[end] - prefix[start-1])
+							);
+						}
+					}
+				}
+
+				sb.append(dp[1][K]).append("\n");
+			}
+
+			System.out.println(sb.toString());
+		}
+	}
+}