diff --git a/ACMOJ-1071.cpp b/ACMOJ-1071.cpp
new file mode 100644
index 0000000..4b907d3
--- /dev/null
+++ b/ACMOJ-1071.cpp
@@ -0,0 +1,144 @@
+#include <bits/stdc++.h>
+
+class LinkList {
+  struct Node {
+    int val;
+    Node *next;
+    Node() : val(0), next(nullptr) {}
+    Node(int __val, Node *__next) : val(__val), next(__next) {}
+  };
+  int count = 0;
+  Node *head = nullptr;
+
+ public:
+  LinkList() { ; }
+  ~LinkList() {
+    Node *p = head;
+    while (p != nullptr) {
+      Node *next_p = p->next;
+      delete p;
+      p = next_p;
+    }
+  }
+  void push(int new_val) {
+    if (count == 0) {
+      head = new Node(new_val, nullptr);
+      count = 1;
+      return;
+    }
+    Node *cur = head, *last_cur = nullptr;
+    while (cur != nullptr) {
+      if (cur->val >= new_val) {
+        if (last_cur != nullptr) {
+          last_cur->next = new Node(new_val, cur);
+        } else {
+          head = new Node(new_val, cur);
+        }
+        count++;
+        return;
+      }
+      last_cur = cur;
+      cur = cur->next;
+    }
+    // std::cerr << last_cur << std::endl;
+    last_cur->next = new Node(new_val, cur);
+    count++;
+  }
+  int getKth(int idx) {
+    if (idx >= count) return -1;
+    Node *cur = head;
+    for (int i = 0; i < idx && cur != nullptr; i++) cur = cur->next;
+    return cur->val;
+  }
+  void merge(LinkList *oth) {
+    count += oth->count;
+    Node *cur_this = head, *cur_oth = oth->head;
+    head = nullptr;
+    Node *head_store = nullptr;
+    while (cur_this != nullptr && cur_oth != nullptr) {
+      if (cur_this->val <= cur_oth->val) {
+        if (head == nullptr) {
+          head_store = head = cur_this;
+        } else {
+          head->next = cur_this;
+          head = head->next;
+        }
+        cur_this = cur_this->next;
+      } else {
+        if (head == nullptr) {
+          head_store = head = cur_oth;
+        } else {
+          head->next = cur_oth;
+          head = head->next;
+        }
+        cur_oth = cur_oth->next;
+      }
+    }
+    while (cur_this != nullptr) {
+      if (head == nullptr) {
+        head_store = head = cur_this;
+      } else {
+        head->next = cur_this;
+        head = head->next;
+      }
+      cur_this = cur_this->next;
+    }
+    while (cur_oth != nullptr) {
+      if (head == nullptr) {
+        head_store = head = cur_oth;
+      } else {
+        head->next = cur_oth;
+        head = head->next;
+      }
+      cur_oth = cur_oth->next;
+    }
+    if (head != nullptr) head->next = nullptr;
+    head = head_store;
+    oth->count = 0;
+    oth->head = nullptr;
+  }
+};
+
+class LinkListArray {
+ private:
+  int len;
+  LinkList **lists;
+
+ public:
+  LinkListArray(int n) : len(n) {
+    lists = new LinkList *[n];
+    for (int i = 0; i < n; ++i) lists[i] = new LinkList;
+  }
+  ~LinkListArray() {
+    for (int i = 0; i < len; ++i) {
+      delete lists[i];
+    }
+    delete[] lists;
+  }
+
+  void insertNumber(int n, int x) { lists[n]->push(x); }
+  int queryNumber(int n, int k) { return lists[n]->getKth(k); }
+  void mergeLists(int p, int q) { lists[p]->merge(lists[q]); }
+};
+
+int main() {
+#ifdef local
+  freopen("pro.in", "r", stdin);
+#endif
+  int len, m;
+  scanf("%d%d", &len, &m);
+  LinkListArray a = LinkListArray(len);
+  for (int i = 0, op, s1, s2; i < m; ++i) {
+    scanf("%d%d%d", &op, &s1, &s2);
+    if (op == 0) {
+      a.insertNumber(s1, s2);
+    }
+    if (op == 1) {
+      printf("%d\n", a.queryNumber(s1, s2));
+    }
+    if (op == 2) {
+      a.mergeLists(s1, s2);
+    }
+  }
+  return 0;
+}
\ No newline at end of file
diff --git a/ACMOJ-1072.cpp b/ACMOJ-1072.cpp
new file mode 100644
index 0000000..6e7793d
--- /dev/null
+++ b/ACMOJ-1072.cpp
@@ -0,0 +1,76 @@
+#include <iomanip>
+#include <iostream>
+using namespace std;
+
+class CircleSet {
+  friend istream &operator>>(istream &in, CircleSet &obj);
+
+ private:
+  struct Circle {
+    long long x, y, r;
+    Circle(long long _x = 0, long long _y = 0, long long _r = 0)
+        : x(_x), y(_y), r(_r) {}
+  };
+  int count;        // 集合中圆的数目
+  Circle *circles;  // 集合中所有圆
+ public:
+  CircleSet(int n) : count(n) {
+    circles = new Circle[n];
+    count = n;
+  }
+  ~CircleSet() { delete[] circles; }
+  int operator[](int idx) const noexcept { return circles[idx].r; }
+  bool checkContaining(int p, int q) {
+    if (circles[p].r <= circles[q].r) return false;
+    return (circles[p].x - circles[q].x) * (circles[p].x - circles[q].x) +
+               (circles[p].y - circles[q].y) * (circles[p].y - circles[q].y) <
+           (circles[p].r - circles[q].r) * (circles[p].r - circles[q].r);
+  }
+  int getCircleContainingQ(int q) {
+    int res = -1;
+    for (int p = 0; p < count; p++) {
+      if (!checkContaining(p, q)) continue;
+      if (res == -1)
+        res = circles[p].r;
+      else
+        res = (circles[p].r < res) ? circles[p].r : res;
+    }
+    return res;
+  }
+};
+
+istream &operator>>(istream &in, CircleSet &obj) {
+  for (int i = 0; i < obj.count; ++i) {
+    in >> obj.circles[i].x >> obj.circles[i].y >> obj.circles[i].r;
+  }
+  return in;
+}
+
+int main() {
+#ifdef local
+  freopen("pro.in", "r", stdin);
+#endif
+  int n, m, type;
+  cin >> n >> m;
+  CircleSet set(n);
+  cin >> set;  // 输入集合中的所有圆
+  while (m--) {
+    int type, p, q;
+    cin >> type;
+    if (type == 1) {
+      // do nothing
+    } else if (type == 2) {
+      for (int i = 0; i < n; ++i) {
+        cout << set[i] << ' ';
+      }
+      cout << endl;
+    } else if (type == 3) {
+      cin >> p >> q;
+      cout << set.checkContaining(p, q) << endl;
+    } else if (type == 4) {
+      cin >> q;
+      cout << set.getCircleContainingQ(q) << endl;
+    }
+  }
+  return 0;
+}
\ No newline at end of file
diff --git a/ACMOJ-1073.cpp b/ACMOJ-1073.cpp
new file mode 100644
index 0000000..1db116d
--- /dev/null
+++ b/ACMOJ-1073.cpp
@@ -0,0 +1,185 @@
+#include <cstdio>
+#include <cstdlib>
+#include <iostream>
+using namespace std;
+const int month_days[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+class Date {
+ private:
+  int _year;
+  int _month;
+  int _day;
+
+  static bool IsValid(int year, int month, int day) {
+    if (month < 1 || month > 12) return false;
+    if (month != 2) return 1 <= day && day <= month_days[month];
+    return 1 <= day && day <= month_days[month] + IsLeapYear(year);
+  }
+  static Date *bucket;
+  static int bucket_cnt, it_cnt;
+  static int GetId(const Date &dt) {
+    if (bucket == nullptr) {
+      bucket = new Date[49275];
+      for (int year = 1900; year <= 2030; year++)
+        for (int month = 1; month <= 12; month++) {
+          int ds = month_days[month];
+          if (month == 2 && IsLeapYear(year)) ds++;
+          for (int day = 1; day <= ds; day++) {
+            bucket[bucket_cnt++] = Date(year, month, day);
+          }
+        }
+    }
+    int L = 0, R = bucket_cnt, M;
+    while (L < R) {
+      M = (L + R) >> 1;
+      if (bucket[M] < dt)
+        L = M + 1;
+      else if (dt < bucket[M])
+        R = M;
+      else
+        return M;
+    }
+    return (L + R) >> 1;
+  }
+
+ public:
+  // 构造函数
+  Date() : _year(0), _month(0), _day(0) {
+    it_cnt++;
+    _year = 1900;
+    _month = 1;
+    _day = 1;
+  }
+  Date(int yy, int mm, int dd) {
+    it_cnt++;
+    if (!IsValid(yy, mm, dd)) {
+      _year = 1900;
+      _month = 1;
+      _day = 1;
+      return;
+    }
+    _year = yy;
+    _month = mm;
+    _day = dd;
+  }
+  ~Date() {
+    it_cnt--;
+    if (it_cnt == 0) {
+      delete[] bucket;
+      bucket = nullptr;
+      bucket_cnt = 0;
+    }
+  }
+  // 判断是否为闰年
+  static bool IsLeapYear(int year) {
+    if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
+      return true;
+    } else {
+      return false;
+    }
+  }
+  // 一个日期加上一个天数
+  Date operator+(int det) {
+    int id = GetId(*this);
+    return bucket[id + det];
+  }
+  // 一个日期减去一个天数
+  Date operator-(int det) {
+    int id = GetId(*this);
+    return bucket[id - det];
+  }
+  // 前置++
+  Date &operator++() {
+    *this = *this + 1;
+    return *this;
+  }
+  // 后置++
+  Date operator++(int) {
+    Date tmp = *this;
+    *this = *this + 1;
+    return tmp;
+  }
+  // 前置--
+  Date &operator--() {
+    *this = *this - 1;
+    return *this;
+  }
+  // 后置--
+  Date operator--(int) {
+    Date tmp = *this;
+    *this = *this - 1;
+    return tmp;
+  }
+  int operator-(const Date &B) {
+    int ida = GetId(*this);
+    int idb = GetId(B);
+    return ida > idb ? ida - idb : idb - ida;
+  }
+  //<重载
+  bool operator<(const Date &B) const {
+    if (_year != B._year) return _year < B._year;
+    if (_month != B._month) return _month < B._month;
+    return _day < B._day;
+  }
+  // 重载输出运算符
+  friend ostream &operator<<(ostream &stream, const Date &dt);
+  // 以上仅为提示，不代表你需要完成所有，你也可以添加其他需要的函数。
+};
+Date *Date::bucket = nullptr;
+int Date::it_cnt = 0;
+int Date::bucket_cnt = 0;
+ostream &operator<<(ostream &stream, const Date &dt) {
+  stream << dt._year << '-' << dt._month << '-' << dt._day;
+  return stream;
+}
+
+void Test() {
+  int op;
+  cin >> op;
+  int yy, mm, dd;
+  if (op == 1 || op == 0) {
+    Date d0;
+    Date d1(2000, 2, 29);
+    Date d2(1900, 2, 29);
+    cout << d0 << endl;
+    cout << d1 << endl;
+    cout << d2 << endl;
+    // d0.out(); d1.out(); d2.out();
+  }
+  if (op == 2 || op == 0) {
+    cin >> yy >> mm >> dd;
+    Date d0(yy, mm, dd);
+    for (int i = 0; i < 5; ++i) cout << ++d0 << endl;  //(++d0).out();
+    for (int i = 0; i < 5; ++i) cout << d0++ << endl;  //(d0++).out();
+    for (int i = 0; i < 5; ++i) cout << d0-- << endl;  //(d0--).out();
+    for (int i = 0; i < 2; ++i) cout << --d0 << endl;  //(--d0).out();
+    cout << d0 << endl;
+    // d0.out();
+  }
+  if (op == 3 || op == 0) {
+    cin >> yy >> mm >> dd;
+    Date d0(yy, mm, dd);
+    cout << d0 + 100 << endl;
+    // (d0+100).out();
+    cout << d0 - 1000 << endl;
+    // (d0-1000).out();
+  }
+  if (op == 4 || op == 0) {
+    cin >> yy >> mm >> dd;
+    Date d0(yy, mm, dd);
+    Date d1(2020, 12, 21);
+    cout << (d0 < d1) << endl;
+  }
+  if (op == 5 || op == 0) {
+    cin >> yy >> mm >> dd;
+    Date d0(yy, mm, dd);
+    Date d1(1912, 6, 23);
+    cout << d0 - d1 << endl;
+  }
+}
+int main() {
+#ifdef local
+  freopen("pro.in", "r", stdin);
+#endif
+  Test();
+  return 0;
+}
\ No newline at end of file
diff --git a/ACMOJ-1448.cpp b/ACMOJ-1448.cpp
new file mode 100644
index 0000000..c617469
--- /dev/null
+++ b/ACMOJ-1448.cpp
@@ -0,0 +1,112 @@
+#include "ACMOJ-1448.hpp"
+
+#include <iostream>
+#include <vector>
+
+#include "task.hpp"
+
+using namespace std;
+
+namespace cpu_testing {
+enum operationType { AddTask, ChangePriority };
+
+struct Operation {
+  operationType type;
+  uint trig_time;
+  sjtu::Task task;
+
+  Operation(operationType _type, uint _trig_time, const sjtu::Task &_task)
+      : task(_task) {
+    type = _type;
+    trig_time = _trig_time;
+  }
+
+  ~Operation() = default;
+};
+
+vector<Operation> readInputs() {
+  vector<Operation> operations;
+  int m, op;
+  uint trig_time, task_id, priority, time;
+  cin >> m;
+  for (int i = 0; i < m; ++i) {
+    cin >> op >> trig_time;
+    if (op == 0) {
+      cin >> task_id >> priority >> time;
+      operations.emplace_back(
+          Operation(AddTask, trig_time, sjtu::Task(task_id, priority, time)));
+    } else {
+      cin >> task_id >> priority;
+      operations.emplace_back(
+          Operation(ChangePriority, trig_time, sjtu::Task(task_id, priority)));
+    }
+  }
+  return operations;
+}
+
+void processOutputs(const vector<pair<sjtu::CPUState, uint> > &ans) {
+  for (auto log : ans) {
+    if (log.first == sjtu::busy && log.second == 0) {
+      cerr << "[Error] Busy CPU is not processing any task.\n";
+      exit(1);
+    }
+    if (log.first == sjtu::idle && log.second != 0) {
+      cerr << "[Error] Idle CPU is still processing tasks.\n";
+      exit(1);
+    }
+    cout << log.first << ' ' << log.second << endl;
+  }
+}
+}  // namespace cpu_testing
+
+int main() {
+#ifdef local
+  freopen("pro.in", "r", stdin);
+  freopen("pro.out", "w", stdout);
+#endif
+  ios::sync_with_stdio(false);
+  cin.tie(nullptr), cout.tie(nullptr);
+
+  vector<cpu_testing::Operation> operations(cpu_testing::readInputs());
+
+  sjtu::CPU *processor;
+  int CPUType;
+  cin >> CPUType;
+  switch (CPUType) {
+    case 0:
+      processor = new sjtu::CPU_FCFS();
+      break;
+    case 1:
+      processor = new sjtu::CPU_SRTF();
+      break;
+    case 2:
+      processor = new sjtu::CPU_PRIORITY();
+      break;
+    default:
+      cerr << "[Error] Unexpected CPU type.";
+      return 1;
+  }
+
+  vector<pair<sjtu::CPUState, uint> > ans;
+  int time = 0, cur = 0;
+  while (time <= 1000) {
+    while (cur < operations.size() && operations[cur].trig_time == time) {
+      int success = 0;
+      if (operations[cur].type == cpu_testing::AddTask)
+        success = processor->addTask(operations[cur].task);
+      if (operations[cur].type == cpu_testing::ChangePriority)
+        success = processor->changePriority(operations[cur].task.task_id,
+                                            operations[cur].task.priority);
+      if (success == 0) {
+        cerr << "[Error] Fail to execute operation " << cur << ".\n";
+      }
+      ++cur;
+    }
+    ans.push_back(processor->run());
+    ++time;
+  }
+
+  cpu_testing::processOutputs(ans);
+  delete processor;
+  return 0;
+}
\ No newline at end of file
diff --git a/ACMOJ-1448.hpp b/ACMOJ-1448.hpp
new file mode 100644
index 0000000..5d21025
--- /dev/null
+++ b/ACMOJ-1448.hpp
@@ -0,0 +1,130 @@
+#ifndef _SJTU_CPP_FINAL_CPU_HPP_
+#define _SJTU_CPP_FINAL_CPU_HPP_
+
+#include <cassert>
+#include <vector>
+
+#include "task.hpp"
+
+using namespace std;
+
+typedef unsigned int uint;
+
+namespace sjtu {
+// CPU base class, modifications is not allowed.
+class CPU {
+ protected:
+  CPUState state;
+  vector<Task> tasks;
+
+ public:
+  CPU() : tasks() { state = idle; }
+
+  // Add a new task.
+  int addTask(const Task &t) {
+    tasks.push_back(t);
+    return 1;
+  }
+
+  // Change the priority of one process, return 1 if success and return 0 if
+  // fail.
+  int changePriority(uint task_id, uint priority) {
+    for (auto &task : tasks)
+      if (task.task_id == task_id) {
+        task.priority = priority;
+        return 1;
+      }
+    return 0;
+  }
+
+  virtual pair<CPUState, uint> run() = 0;
+
+  virtual ~CPU() = default;
+};
+
+// FCFS method based CPU.
+class CPU_FCFS : public CPU {
+  // TODO: complete the FCFS method.
+ public:
+  pair<CPUState, uint> run() override {
+    bool has_opt = false;
+    for (int i = 0; i < tasks.size(); i++) {
+      if (tasks[i].time > 0) {
+        has_opt = true;
+        state = CPUState::busy;
+        tasks[i].time--;
+        return std::make_pair(CPUState::busy, tasks[i].task_id);
+      }
+    }
+    state = CPUState::idle;
+    return std::make_pair(CPUState::idle, 0);
+  }
+  ~CPU_FCFS() override = default;
+};
+
+// SRTF method based CPU.
+class CPU_SRTF : public CPU {
+  // TODO: complete the SRTF method.
+ public:
+  pair<CPUState, uint> run() override {
+    bool has_opt = false;
+    int least_time = -1;
+    for (int i = 0; i < tasks.size(); i++) {
+      if (tasks[i].time > 0) {
+        has_opt = true;
+        if (least_time == -1)
+          least_time = tasks[i].time;
+        else
+          least_time =
+              (tasks[i].time < least_time) ? tasks[i].time : least_time;
+      }
+    }
+    if (!has_opt) {
+      state = CPUState::idle;
+      return std::make_pair(CPUState::idle, 0);
+    }
+    for (int i = 0; i < tasks.size(); i++) {
+      if (tasks[i].time == least_time) {
+        state = CPUState::busy;
+        tasks[i].time--;
+        return std::make_pair(CPUState::busy, tasks[i].task_id);
+      }
+    }
+  }
+  ~CPU_SRTF() override = default;
+};
+
+// priority method based CPU.
+class CPU_PRIORITY : public CPU {
+  // TODO: complete the priority method.
+ public:
+  pair<CPUState, uint> run() override {
+    bool has_opt = false;
+    int highest_pri = -1;
+    for (int i = 0; i < tasks.size(); i++) {
+      if (tasks[i].time > 0) {
+        has_opt = true;
+        if (highest_pri == -1)
+          highest_pri = tasks[i].priority;
+        else
+          highest_pri = (tasks[i].priority < highest_pri) ? tasks[i].priority
+                                                          : highest_pri;
+      }
+    }
+    if (!has_opt) {
+      state = CPUState::idle;
+      return std::make_pair(CPUState::idle, 0);
+    }
+    for (int i = 0; i < tasks.size(); i++) {
+      if (tasks[i].priority == highest_pri && tasks[i].time > 0) {
+        state = CPUState::busy;
+        tasks[i].time--;
+        return std::make_pair(CPUState::busy, tasks[i].task_id);
+      }
+    }
+  }
+  ~CPU_PRIORITY() override = default;
+};
+}  // namespace sjtu
+
+#endif
\ No newline at end of file