From 5d314398b80b936ad31713dc8ed8663038dde315 Mon Sep 17 00:00:00 2001
From: manoflearning <77jwk0724@gmail.com>
Date: Mon, 29 Dec 2025 19:18:42 +0900
Subject: [PATCH 1/2] feat: add multiset pbds

---
 src/1-ds/pbds.cpp | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/1-ds/pbds.cpp b/src/1-ds/pbds.cpp
index 3ed73ae..3f4c488 100644
--- a/src/1-ds/pbds.cpp
+++ b/src/1-ds/pbds.cpp
@@ -2,7 +2,15 @@
 #include <ext/pb_ds/assoc_container.hpp>
 #include <ext/pb_ds/tree_policy.hpp>
 using namespace __gnu_pbds;
-using ordered_set = tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>;
-ordered_set st;
+using pbds = tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>;
+pbds st;
 st.order_of_key(x);  // number of elements strictly less than x
-st.find_by_order(x); // value of xth element (0-based)
\ No newline at end of file
+st.find_by_order(x); // value of xth element (0-based)
+
+// multiset pbds (use "less_equal<int>" and custom "m_erase")
+using multi_pbds = tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>;
+void m_erase(multi_pbds &OS, int val){
+    int index = OS.order_of_key(val);
+    multi_pbds::iterator it = OS.find_by_order(index);
+    OS.erase(it);
+}

From 14389194d874bd6794b279865c9bd63a02292ade Mon Sep 17 00:00:00 2001
From: manoflearning <77jwk0724@gmail.com>
Date: Mon, 29 Dec 2025 19:21:07 +0900
Subject: [PATCH 2/2] fix

---
 src/1-ds/pbds.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/1-ds/pbds.cpp b/src/1-ds/pbds.cpp
index 3f4c488..87af3a4 100644
--- a/src/1-ds/pbds.cpp
+++ b/src/1-ds/pbds.cpp
@@ -9,8 +9,8 @@ st.find_by_order(x); // value of xth element (0-based)
 
 // multiset pbds (use "less_equal<int>" and custom "m_erase")
 using multi_pbds = tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update>;
-void m_erase(multi_pbds &OS, int val){
-    int index = OS.order_of_key(val);
-    multi_pbds::iterator it = OS.find_by_order(index);
-    OS.erase(it);
+void m_erase(multi_pbds &OS, int val) {
+  int index = OS.order_of_key(val);
+  multi_pbds::iterator it = OS.find_by_order(index);
+  OS.erase(it);
 }