P4035 [JSOI2008]球形空间产生器

https://www.luogu.com.cn/record/75423418

Luogu/P4035/P4035.cpp

@@ -0,0 +1,56 @@
+#include <algorithm>
+#include <cmath>
+#include <iomanip>
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 15;
+const double eps = 1e-6;
+
+int n;
+double a[N][N], b[N][N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> n;
+
+    for (int i = 1; i <= n + 1; i++) {
+        for (int j = 1; j <= n; j++) {
+            cin >> a[i][j];
+        }
+    }
+
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= n; j++) {
+            b[i][j] = 2.0 * (a[i][j] - a[i + 1][j]);
+            b[i][n + 1] += std::pow(a[i][j], 2) - std::pow(a[i + 1][j], 2);
+        }
+    }
+
+    for (int i = 1; i <= n; i++) {
+        for (int j = i; j <= n; j++) {
+            if (std::abs(b[j][i]) > eps) {
+                std::swap(b[i], b[j]);
+            }
+        }
+
+        for (int j = 1; j <= n; j++) {
+            if (i == j) continue;
+            double x = b[j][i] / b[i][i];
+            for (int k = i; k <= n + 1; k++) {
+                b[j][k] -= b[i][k] * x;
+            }
+        }
+    }
+
+    for (int i = 1; i <= n; i++) {
+        cout << std::fixed << std::setprecision(3) << b[i][n + 1] / b[i][i] << ' ';
+    }
+    cout << endl;
+
+    return 0;
+}