add vector

vector/src/utility.hpp

@@ -0,0 +1,27 @@
+#ifndef SJTU_UTILITY_HPP
+#define SJTU_UTILITY_HPP
+
+#include <utility>
+
+namespace sjtu {
+
+template<class T1, class T2>
+class pair {
+public:
+	T1 first;
+	T2 second;
+	constexpr pair() : first(), second() {}
+	pair(const pair &other) = default;
+	pair(pair &&other) = default;
+	pair(const T1 &x, const T2 &y) : first(x), second(y) {}
+	template<class U1, class U2>
+	pair(U1 &&x, U2 &&y) : first(x), second(y) {}
+	template<class U1, class U2>
+	pair(const pair<U1, U2> &other) : first(other.first), second(other.second) {}
+	template<class U1, class U2>
+	pair(pair<U1, U2> &&other) : first(other.first), second(other.second) {}
+};
+
+}
+
+#endif