Upd: 加入了一些非常毒瘤的 corner case 测试点。

data/Integer3/3.cpp

@@ -0,0 +1,26 @@
+/*
+Time: 2023-10-20
+Test: Copy constructor and assignment operator.
+std Time: 0.30s
+Time Limit: 1.00s
+Notes: Sanity check.
+*/
+
+#include "int2048.h"
+
+void sanity_check(sjtu::int2048 &x) {
+    x = x = x = x = x = x = x = x = x;
+    sjtu::int2048 y = (((((((((((((x)))))))))))));
+    sjtu::int2048 z = (((((((-(((((x))))))))))));
+    x = ( x = (x = (x = y + z + x)));
+}
+
+signed main() {
+    sjtu::int2048 x {"111111111111111111111111111111111111111111111111111111111111111111111111112"};
+    sanity_check(x);
+    std::cout << x << '\n';
+    std::cout << -sjtu::int2048{0} << '\n';
+    x.read("-0");
+    std::cout << x << '\n';
+    return 0;
+}