diff --git a/Data Structure 2/2075.cpp b/Data Structure 2/2075.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..e2523f2c98a84609b66144fe6bbd8dfacf224cbb
--- /dev/null
+++ b/Data Structure 2/2075.cpp
@@ -0,0 +1,34 @@
+#include<iostream>
+#include<queue>
+using namespace std;
+
+int main()
+{
+ ios_base::sync_with_stdio(false);
+ cin.tie(NULL);
+
+ int N;
+ cin >> N;
+
+ priority_queue<int, vector<int>, greater<int>> pq;
+
+ for(int i=0;i<N*N;i++)
+ {
+ int num;
+ cin >> num;
+
+ if(pq.size() < N)
+ pq.push(num);
+ else
+ {
+ if(pq.top() < num)
+ {
+ pq.pop();
+ pq.push(num);
+ }
+
+ }
+ }
+
+ cout << pq.top();
+}
\ No newline at end of file
diff --git a/Data Structure 2/21939.cpp b/Data Structure 2/21939.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..faa6fcbc8b6bf3c3129ff5de075d44983ab700de
--- /dev/null
+++ b/Data Structure 2/21939.cpp
@@ -0,0 +1,102 @@
+#include<iostream>
+#include<queue>
+#include<map>
+using namespace std;
+
+struct problem
+{
+ int idx, level;
+};
+
+struct compare_max
+{
+ bool operator()(const problem& p1, const problem& p2)
+ {
+ if(p1.level == p2.level)
+ return p1.idx < p2.idx;
+ return p1.level < p2.level;
+ }
+};
+struct compare_min
+{
+ bool operator()(const problem& p1, const problem& p2)
+ {
+ if(p1.level == p2.level)
+ return p1.idx > p2.idx;
+ return p1.level > p2.level;
+ }
+};
+
+int main()
+{
+ ios_base::sync_with_stdio(false);
+ cin.tie(NULL);
+ cout.tie(NULL);
+
+ int N;
+ cin >> N;
+
+ map<int, int> diff;
+ priority_queue<problem, vector<problem>, compare_max> max_heap;
+ priority_queue<problem, vector<problem>, compare_min> min_heap;
+
+ for(int i=0;i<N;i++)
+ {
+ problem input;
+ cin >> input.idx >> input.level;
+
+ max_heap.push(input);
+ min_heap.push(input);
+ diff[input.idx] = input.level;
+ }
+
+
+
+ int M;
+ cin >> M;
+
+ for(int i=0;i<M;i++)
+ {
+ string op;
+ cin >> op;
+
+ if(op == "add")
+ {
+ problem input;
+ cin >> input.idx >> input.level;
+
+ max_heap.push(input);
+ min_heap.push(input);
+ diff[input.idx] = input.level;
+ }
+ else if(op == "recommend")
+ {
+ int x;
+ cin >> x;
+
+ if(x == 1)
+ {
+ while(!max_heap.empty() && diff[max_heap.top().idx] != max_heap.top().level)
+ max_heap.pop();
+
+ cout << max_heap.top().idx << "\n";
+
+ }
+ else
+ {
+ while(!min_heap.empty() && diff[min_heap.top().idx] != min_heap.top().level)
+ min_heap.pop();
+
+ cout << min_heap.top().idx << "\n";
+ min_heap.pop();
+ }
+ }
+ else if(op == "solved")
+ {
+ int x;
+ cin >> x;
+
+ diff[x] = 0;
+ }
+ }
+}
\ No newline at end of file
diff --git a/Data Structure 2/21942.cpp b/Data Structure 2/21942.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..401a86431cb30d3d89d516ed1c1dc4e911234fa1
--- /dev/null
+++ b/Data Structure 2/21942.cpp
@@ -0,0 +1,76 @@
+#include<iostream>
+#include<map>
+#include<string>
+using namespace std;
+
+#define int int64_t
+
+struct books{
+ int v{};
+ map<string, int> table;
+};
+
+map<string, books> Map;
+
+int32_t main()
+{
+ ios_base::sync_with_stdio(false);
+ cin.tie(NULL);
+ cout.tie(NULL);
+
+ int month[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+
+ int N, L, F;
+ string string_L;
+
+ cin >> N >> string_L >> F;
+
+ int Day_L = stoi(string_L.substr(0,3));
+ int Hour_L = stoi(string_L.substr(4,2));
+ int Minute_L = stoi(string_L.substr(7,2));
+
+ L = Day_L * 1440 + Hour_L * 60 + Minute_L;
+
+ while(N--)
+ {
+ string date, time, P, M;
+ cin >> date >> time >> P >> M;
+
+ int Time;
+
+ int Month = stoi(date.substr(5,2));
+ int Day = stoi(date.substr(8,2));
+ int Hour = stoi(time.substr(0,2));
+ int Minute = stoi(time.substr(3,2));
+
+ int Month_cum = 0;
+ for(int i=0;i<Month;i++)
+ Month_cum += month[i];
+
+ Time = Month_cum * 1440 + Day * 1440 + Hour * 60 + Minute;
+
+ auto& chk = Map[M];
+ if(chk.table.count(P))
+ {
+ if((Time - chk.table[P] - L) > 0)
+ chk.v += (Time - chk.table[P] - L) * F;
+ chk.table.erase(P);
+ }
+ else
+ chk.table[P] = Time;
+ }
+
+ bool chk = false;
+ auto iter = Map.begin();
+ while(iter != Map.end())
+ {
+ if(iter->second.v != 0)
+ {
+ chk = true;
+ cout << iter->first << " " << iter->second.v << "\n";
+ }
+ iter++;
+ }
+ if(chk == false)
+ cout << -1 << '\n';
+}
\ No newline at end of file
diff --git a/Data Structure 2/21944.cpp b/Data Structure 2/21944.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..fa3ee7b0f43bcf0c704eec01a5015f5ce6eece4f
--- /dev/null
+++ b/Data Structure 2/21944.cpp
@@ -0,0 +1,128 @@
+#include<iostream>
+#include<string>
+#include<vector>
+#include<queue>
+#include<map>
+#include<set>
+using namespace std;
+
+set<pair<int,int>> Q1[101];
+set<pair<int,int>> Q2;
+set<pair<int,int>> Q3; // 난이도, 번호
+
+int level[100001];
+int algo[100001];
+
+
+void insert(int P, int L, int G)
+{
+ Q1[G].insert(make_pair(L, P));
+ Q2.insert(make_pair(L, P));
+ Q3.insert(make_pair(L, P));
+}
+int re1(int G, int x)
+{
+ if(x == 1)
+ return prev(Q1[G].end())->second;
+ else
+ return Q1[G].begin()->second;
+}
+int re2(int x)
+{
+ if(x==1)
+ return prev(Q2.end())->second;
+ else
+ return Q2.begin()->second;
+}
+int re3(int x, int L)
+{
+ if(x==1)
+ {
+ auto iter = Q3.upper_bound(make_pair(L-1, 999999));
+ if(iter == Q3.end())
+ return -1;
+ else
+ return iter->second;
+ }
+ else
+ {
+ auto iter = Q3.upper_bound(make_pair(L, -1));
+ if(iter == Q3.begin())
+ return -1;
+ else
+ return prev(iter)->second;
+ }
+}
+void del(int P)
+{
+ int L = level[P];
+ int G = algo[P];
+
+ Q1[G].erase(make_pair(L, P));
+ Q2.erase(make_pair(L, P));
+ Q3.erase(make_pair(L, P));
+}
+
+int main()
+{
+ ios_base::sync_with_stdio(false);
+ cin.tie(NULL);
+ cout.tie(NULL);
+
+ int N;
+ cin >> N;
+
+ while(N--)
+ {
+ int P, L, G;
+ cin >> P >> L >> G;
+
+ insert(P, L, G);
+ level[P] = L;
+ algo[P] = G;
+ }
+
+ int M;
+ cin >> M;
+
+ while(M--)
+ {
+ string query;
+ cin >> query;
+
+ if(query == "recommend")
+ {
+ int G, x;
+ cin >> G >> x;
+ cout << re1(G, x) << endl;
+ }
+ else if(query == "recommend2")
+ {
+ int x;
+ cin >> x;
+ cout << re2(x) << endl;
+ }
+ else if(query == "recommend3")
+ {
+ int x, L;
+ cin >> x >> L;
+ cout << re3(x, L) << endl;
+ }
+ else if(query == "add")
+ {
+ int P, L, G;
+ cin >> P >> L >> G;
+
+ insert(P, L, G);
+ level[P] = L;
+ algo[P] = G;
+ }
+ else if(query == "solved")
+ {
+ int P;
+ cin >> P;
+
+ del(P);
+ }
+ }
+}
\ No newline at end of file
diff --git a/Data Structure 2/2696.cpp b/Data Structure 2/2696.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..f7a345dc22599af7e02218a75e367479548efed1
--- /dev/null
+++ b/Data Structure 2/2696.cpp
@@ -0,0 +1,54 @@
+#include<iostream>
+#include<vector>
+#include<queue>
+using namespace std;
+
+int main()
+{
+ ios_base::sync_with_stdio(false);
+ cin.tie(NULL);
+ cout.tie(NULL);
+
+ int T;
+ cin >> T;
+ while(T--)
+ {
+ int M;
+ vector<int> ans;
+ priority_queue<int, vector<int>, less<int>> max_heap;
+ priority_queue<int, vector<int>, greater<int>>min_heap;
+
+ cin >> M;
+
+ for(int i=1;i<=M;i++)
+ {
+ int num;
+ cin >> num;
+
+ if(max_heap.size() == min_heap.size())
+ max_heap.push(num);
+ else
+ min_heap.push(num);
+
+ if(!max_heap.empty() && !min_heap.empty() && min_heap.top() < max_heap.top())
+ {
+ int toMin = max_heap.top();
+ int toMax = min_heap.top();
+
+ max_heap.pop();
+ min_heap.pop();
+
+ max_heap.push(toMax);
+ min_heap.push(toMin);
+ }
+
+ if(i%2==1)
+ ans.push_back(max_heap.top());
+ }
+
+ cout << ans.size() << endl;
+ for(int i=0;i<ans.size();i++)
+ cout << ans[i] << ' ';
+ cout << endl;
+ }
+}
\ No newline at end of file