add missing files

1 files changed, 18 insertions, 0 deletions

diff --git a/datastructures/pbds.cpp b/datastructures/pbds.cpp
new file mode 100644
index 0000000..c2b44cc
--- /dev/null
+++ b/datastructures/pbds.cpp
@@ -0,0 +1,18 @@
+#include <ext/pb_ds/assoc_container.hpp>
+using namespace __gnu_pbds;
+template<typename T>
+using Tree = tree<T, null_type, less<T>, rb_tree_tag,
+                  tree_order_statistics_node_update>;
+// T.order_of_key(x): number of elements strictly less than x
+// *T.find_by_order(k): k-th element
+
+template<typename T>
+struct chash {
+	const uint64_t C = ll(2e18 * acos(-1)) | 199; // random odd
+	size_t operator()(T o) const {
+		return __builtin_bswap64(hash<T>()(o) * C);
+}};
+template<typename K, typename V>
+using hashMap = gp_hash_table<K, V, chash<K>>;
+template<typename T>
+using hashSet = gp_hash_table<T, null_type, chash<T>>;