Prevent swapping two equal items

It should be a lot faster now, although the answers might be a little
worse

main.cpp

@@ -12,7 +12,7 @@
 #endif
 
 #ifndef TEMP_MIN
-#define TEMP_MIN 0.01
+#define TEMP_MIN 10
 #endif
 
 int main(int argc, char *argv[])

sa.hpp

@@ -65,7 +65,8 @@ class box {
 	auto swappable11(box &other, int capacity) -> bool {
 		long long choice1 = items.top();
 		long long choice2 = other.items.top();
-		return choice1 + other.fullness - choice2 <= capacity &&
+		return choice1 != choice2 &&
+		       choice1 + other.fullness - choice2 <= capacity &&
 		       choice2 + fullness - choice1 <= capacity;
 	}