first commit

2022-12-15 23:51:04 +07:00
commit 87d51fb251
292 changed files with 12623 additions and 0 deletions
@@ -0,0 +1,23 @@
+import java.util.*;
+
+public class non {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while (t-- > 0) {
+            int n = sc.nextInt();
+            long[] x = new long[n];
+            long[] y = new long[n];
+            for (int i = 0; i < n; i++) {
+                x[i] = sc.nextLong();
+                y[i] = sc.nextLong();
+            }
+            long s = 0;
+            for (int i = 0; i < n; i++) {
+                s += x[i] * y[(i + 1) % n];
+                s -= x[(i + 1) % n] * y[i];
+            }
+            System.out.printf("%.3f\n", Math.abs(s)*0.5);
+        }
+    }
+}