2023.7.31 ~ 8.6

hong/2023 6.5 ~ 6.11/Maximum Product Subarray.java

@@ -0,0 +1,17 @@
+class Solution {
+    int[] cache;
+
+    public int maxProduct(int[] nums) {
+        int max = nums[0];
+		int min = nums[0];
+		int result = nums[0];
+
+		for (int i = 1; i < nums.length; i++) {
+			int temp = max;
+			max = Math.max(Math.max(max * nums[i], min * nums[i]), nums[i]);
+			min = Math.min(Math.min(temp * nums[i], min * nums[i]), nums[i]);
+			result = Math.max(max, result);
+		}
+		return result;
+    }
+}

hong/2023. 07. 31 ~ 8.6/BOJ 1012.java

@@ -0,0 +1,79 @@
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class Main {
+
+	static int test;
+	static int m, n, k;
+	static int[][] map;
+	static int count;
+
+	// 상하좌우
+	final static int[] dy = { -1, 1, 0, 0 };
+	final static int[] dx = { 0, 0, -1, 1 };
+
+	public static void main(String[] args) throws Exception {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		test = Integer.parseInt(br.readLine());
+
+		for (int t = 0; t < test; t++) {
+			init(br);
+
+			for (int y = 0; y < n; y++) {
+				for (int x = 0; x < m; x++) {
+					// 배추가 있고 AND 방문한 적 없음 -> 거기로 이동
+					if (map[y][x] == 1) {
+						dfs(y, x);
+						count++;
+					}
+				}
+			}
+			System.out.println(count);
+		}
+
+	}
+
+	private static void dfs(int y, int x) {
+		map[y][x] = 3;
+
+		// 이동할 수 있음
+		for (int i = 0; i < dy.length; i++) {
+			int ny = y + dy[i];
+			int nx = x + dx[i];
+
+			if (!rangeAvaialable(ny, nx))
+				continue;
+
+			if (map[ny][nx] == 1)
+				dfs(ny, nx);
+		}
+	}
+
+	private static boolean rangeAvaialable(int y, int x) {
+		if (y < 0 || y >= n)
+			return false;
+		if (x < 0 || x >= m)
+			return false;
+		return true;
+	}
+
+	private static void init(BufferedReader br) throws Exception {
+		String line = br.readLine();
+		String[] splited = line.split(" ");
+
+		count = 0;
+		m = Integer.parseInt(splited[0]);
+		n = Integer.parseInt(splited[1]);
+		k = Integer.parseInt(splited[2]);
+		map = new int[n][m];
+
+		for (int i = 0; i < k; i++) {
+			StringTokenizer stk = new StringTokenizer(br.readLine());
+
+			int x = Integer.parseInt(stk.nextToken());
+			int y = Integer.parseInt(stk.nextToken());
+			map[y][x] = 1;
+		}
+	}
+}