add solutions

한민주/20250315/P2156.java

@@ -0,0 +1,50 @@
+package algorithm;
+// 메모리: 13288 kb, 시간: 88ms
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+
+public class P2156 {
+
+	public static void main(String[] args) throws Exception {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		int n = Integer.parseInt(br.readLine());
+		int wine[] = new int[n];
+		int drink[][] = new int[n][2];
+
+		for (int i = 0; i < n; i++) {
+			wine[i] = Integer.parseInt(br.readLine());
+		}
+
+		if (n <= 2) {
+			int sum = 0;
+			for (int i = 0; i < n; i++) {
+				sum += wine[i];
+			}
+			System.out.println(sum);
+			return;
+		}
+		for (int i = 0; i < n; i++) {
+			if (i == 0) {
+				drink[i][0] = wine[i];
+				continue;
+			}
+			if (i == 1) {
+				drink[i][0] = wine[i];
+			}
+			if (i > 1) {
+				drink[i][0] = Math.max(drink[i - 2][0] + wine[i], drink[i - 2][1] + wine[i]);
+			}
+			if (i > 2) {
+				drink[i][0] = Math.max(Math.max(drink[i][0], drink[i - 3][1] + wine[i]), drink[i - 3][0] + wine[i]);
+			}
+			drink[i][1] = drink[i - 1][0] + wine[i];
+		}
+
+		int ans = 0;
+		for (int i = n - 2; i < n; i++) {
+			ans = Math.max(ans, Math.max(drink[i][0], drink[i][1]));
+		}
+		System.out.println(ans);
+	}
+
+}

한민주/20250315/P21758.java

@@ -0,0 +1,52 @@
+package algorithm;
+
+// 메모리: 25296kb, 시간: 192ms
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class P21758 {
+
+	public static void main(String[] args) throws Exception {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		int n = Integer.parseInt(br.readLine());
+
+		if (n == 3) {
+			StringTokenizer st = new StringTokenizer(br.readLine());
+			int a = Integer.parseInt(st.nextToken());
+			int b = Integer.parseInt(st.nextToken());
+			int c = Integer.parseInt(st.nextToken());
+			System.out.println(Math.max(a, Math.max(b, c)) * 2);
+			return;
+		}
+
+		int sum[] = new int[n];
+		StringTokenizer st = new StringTokenizer(br.readLine());
+		sum[0] = Integer.parseInt(st.nextToken());
+		for (int i = 1; i < n; i++) {
+			sum[i] = sum[i - 1] + Integer.parseInt(st.nextToken());
+		}
+
+		int allSum = sum[n - 1];
+		// 벌통이 오른쪽 끝에 있을 때
+		int minus = allSum;
+		for (int i = 1; i < n - 1; i++) {
+			minus = Math.min(minus, sum[i] + sum[i] - sum[i - 1] + sum[0]);
+			if (sum[i] - sum[0] >= minus) {
+				break;
+			}
+		}
+
+		// 벌통이 왼쪽 끝에 있을 때
+		for (int i = n - 2; i > 0; i--) {
+			minus = Math.min(minus, sum[n - 1] - sum[i - 1] + sum[n - 1] - sum[n - 2] + sum[i] - sum[i - 1]);
+			if (sum[n - 1] - sum[i - 1] >= minus) {
+				break;
+			}
+		}
+
+		System.out.println(allSum * 2 - minus);
+
+	}
+
+}

한민주/20250317/P2616.java

@@ -0,0 +1,50 @@
+package algorithm;
+// 메모리: 19992kb, 시간: 156ms
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class P2616 {
+
+	public static void main(String[] args) throws Exception {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		int n = Integer.parseInt(br.readLine());
+
+		int people[] = new int[n];
+		StringTokenizer st = new StringTokenizer(br.readLine());
+		for (int i = 0; i < n; i++) {
+			people[i] = Integer.parseInt(st.nextToken());
+		}
+
+		int k = Integer.parseInt(br.readLine());
+
+		// 누적합 구하기
+		int sum[] = new int[n];
+		for (int i = 0; i < n; i++) {
+			if (i >= 1)
+				sum[i] += people[i] + sum[i - 1];
+			else
+				sum[i] += people[i];
+			if (i >= k) {
+				sum[i] -= people[i - k];
+			}
+		}
+
+		int dp[][] = new int[n][3];
+
+		// i번째
+		for (int i = k - 1; i < n; i++) {
+			dp[i][0] = Math.max(dp[i - 1][0], sum[i]);
+			if (i - k > 0) {
+				dp[i][1] = Math.max(dp[i - 1][1], dp[i - k][0] + sum[i]);
+				dp[i][2] = Math.max(dp[i - 1][2], dp[i - k][1] + sum[i]);
+			}
+		}
+
+
+
+		System.out.println(dp[n - 1][2]);
+	}
+
+}