delete pics to save space

2.10794.cpp

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+// UVa10794 The Deadly Olympic Returns
+// 陈锋
+#include<cmath>
+#include<algorithm>
+#include<cstring>
+#include<cstdio>
+#include<vector>
+#include<cfloat>
+using namespace std;
+
+typedef long long int64;
+
+struct Point3 {
+  int64 x, y, z;
+  Point3(int64 x=0, int64 y=0, int64 z=0):x(x),y(y),z(z) { }
+};
+
+typedef Point3 Vector3;
+
+Vector3 operator + (const Vector3& A, const Vector3& B) { return Vector3(A.x+B.x, A.y+B.y, A.z+B.z); }
+Vector3 operator - (const Point3& A, const Point3& B) { return Vector3(A.x-B.x, A.y-B.y, A.z-B.z); }
+
+int64 Dot(const Vector3& A, const Vector3& B) { return A.x*B.x + A.y*B.y + A.z*B.z; }
+Vector3 Cross(Vector3 A, Vector3 B) { return Vector3(A.y*B.z - A.z*B.y, A.z*B.x - A.x*B.z, A.x*B.y - A.y*B.x); }
+
+int64 readint64()
+{
+    int64 x;
+    scanf("%lld", &x);
+    return x;
+}
+
+Point3 read_point3() {
+  Point3 p;
+  p.x = readint64();
+  p.y = readint64();
+  p.z = readint64();
+  return p;
+}
+
+/********************************************************************/
+
+void solve(int64 c) {
+    printf("Case %d: ", c);
+    readint64();
+    Point3 src1 = read_point3(), dest1 = read_point3();
+    Point3 src2 = read_point3(), dest2 = read_point3();
+    Vector3 v = (dest2 - src2) - (dest1 - src1); // 2相对于1的速度
+    
+    // 求点 src1 到射线 src2, v最短距离
+    double ans;
+    Vector3 ss = src1 - src2;
+    if(Dot(v, v) == 0 || Dot(ss, v) <= 0)
+        ans = sqrt(Dot(ss, ss));
+    else
+    {
+        Vector3 c = Cross(v, ss);
+        ans = Dot(c, c);
+        ans /= Dot(v, v);
+        ans = sqrt(ans);
+    }
+    
+    printf("%.4f\n", ans);
+}
+
+int main()
+{
+    int64 T = readint64();
+    for(int64 i = 1; i <= T; i++) solve(i);
+    return 0;
+}