From cbd56364f50472bfc009c3c7d3f1ca6eebc33af9 Mon Sep 17 00:00:00 2001 From: yang Date: Wed, 18 Oct 2023 15:14:53 +0900 Subject: [PATCH] =?UTF-8?q?14=EC=A3=BC=EC=B0=A8=20=ED=92=80=EC=9D=B4?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- wonjoon/week15/B_2166.java | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 wonjoon/week15/B_2166.java diff --git a/wonjoon/week15/B_2166.java b/wonjoon/week15/B_2166.java new file mode 100644 index 0000000..6b981c1 --- /dev/null +++ b/wonjoon/week15/B_2166.java @@ -0,0 +1,35 @@ +package week15; + +import java.io.BufferedReader; +import java.io.IOException; +import java.io.InputStreamReader; +import java.util.StringTokenizer; + +public class B_2166 { + public static void main(String[] args) throws IOException { + BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); + int n = Integer.parseInt(br.readLine()); + long[][] polygon = new long[n+1][2]; + + for (int i = 0; i < n; i++) { + StringTokenizer st = new StringTokenizer(br.readLine()); + polygon[i][0] = Long.parseLong(st.nextToken()); + polygon[i][1] = Long.parseLong(st.nextToken()); + } + polygon[n][0] = polygon[0][0]; + polygon[n][1] = polygon[0][1]; + + double size = 0; + long a = 0; + long b = 0; + for (int i = 0; i < n; i++) { + a += polygon[i][0]*polygon[i+1][1]; + b += polygon[i][1]*polygon[i+1][0]; + } + + size = Math.abs(a-b)/2.0; + + System.out.println(String.format("%.1f", size)); +// System.out.println(size); + } +}