From fa2197d35860356c7919c64ccbc29d13b722c376 Mon Sep 17 00:00:00 2001
From: Nicholay Shestakov <nicholas.shestakov@gmail.com>
Date: Mon, 15 Dec 2025 15:15:44 +0300
Subject: [PATCH 1/4] Add walker scheme

---
 src/rewriting_hw_1/walker_scheme.py | 73 +++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 src/rewriting_hw_1/walker_scheme.py

diff --git a/src/rewriting_hw_1/walker_scheme.py b/src/rewriting_hw_1/walker_scheme.py
new file mode 100644
index 0000000..16d8218
--- /dev/null
+++ b/src/rewriting_hw_1/walker_scheme.py
@@ -0,0 +1,73 @@
+class WalkerScheme:
+    def __init__(self, events_and_probabilities: list[tuple[str, int]]):
+        if sum(probability[1] for probability in events_and_probabilities) != 1:
+            raise Exception("Сумма вероятностей не равна 1.")
+        self.table = self._get_table(events_and_probabilities)
+
+    def _get_table(self, events_and_probabilities):
+        """Генерирует таблицу Уолкера."""
+        equal_probability = (
+            1 / len(events_and_probabilities)
+        )  # Переменная с вероятностью события, если бы все события были равновероятными.
+        probabilities = {
+            event: equal_probability for event, _ in events_and_probabilities
+        }  # Словарь, где изначально все вероятности эквивалентны и меняются после донорства кого-то кому-то.
+        how_many_added_for_event = {
+            event: 0 for event, _ in events_and_probabilities
+        }  # Для заполнения нерозданных отрезков в конце
+        table = []
+        global_barrier = 0
+
+        for i in range(len(events_and_probabilities)):
+            break_flag = False
+            for donor_event, donor_probability in events_and_probabilities:
+                if donor_probability < probabilities[donor_event]:
+                    for (
+                        recipient_event,
+                        recipient_probability,
+                    ) in events_and_probabilities:
+                        if recipient_probability > probabilities[recipient_event]:
+                            table.append(
+                                (
+                                    donor_event,
+                                    recipient_event,
+                                    global_barrier
+                                    + equal_probability
+                                    - probabilities[donor_event]
+                                    + donor_probability,  # Подсчёт барьера, где к глобальному барьеру прибавляется остаток вероятности донора по модулю эквивалентной вероятности
+                                )
+                            )
+                            global_barrier += equal_probability
+
+                            how_many_added_for_event[recipient_event] += (
+                                equal_probability
+                                - probabilities[donor_event]
+                                + donor_probability
+                            )
+                            how_many_added_for_event[donor_event] += (
+                                probabilities[donor_event] - donor_probability
+                            )
+
+                            probabilities[recipient_event] += (
+                                probabilities[donor_event] - donor_probability
+                            )
+                            probabilities[donor_event] = donor_probability
+
+                            break_flag = True
+                            break
+                    if break_flag:
+                        break
+            else:  # Для оставшихся
+                for event, probability in how_many_added_for_event.items():
+                    print(how_many_added_for_event)
+                    if probability < probabilities[event]:
+                        global_barrier += equal_probability
+                        table.append((event, event, global_barrier))
+                        break
+
+        return table
+
+
+scheme = WalkerScheme([("A", 0.1), ("B", 0.5), ("C", 0.4)])
+
+print(scheme.table)

From 1d5d49a3ebc786389a20d6e288dba1b7e2c32186 Mon Sep 17 00:00:00 2001
From: Nicholay Shestakov <nicholas.shestakov@gmail.com>
Date: Mon, 15 Dec 2025 15:16:01 +0300
Subject: [PATCH 2/4] Add test for walker scheme

---
 tests/walker_scheme_test.py | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 tests/walker_scheme_test.py

diff --git a/tests/walker_scheme_test.py b/tests/walker_scheme_test.py
new file mode 100644
index 0000000..de1cdbf
--- /dev/null
+++ b/tests/walker_scheme_test.py
@@ -0,0 +1,8 @@
+from rewriting_hw_1.walker_scheme import WalkerScheme
+
+
+def test_exception():
+    try:
+        scheme = WalkerScheme([("A", 0.1), ("B", 1)])
+    except Exception as e:
+        assert str(e) == "Сумма вероятностей не равна 1."

From e7dba2c969f203fb72752bb204be17df802eaa57 Mon Sep 17 00:00:00 2001
From: Nicholay Shestakov <nicholas.shestakov@gmail.com>
Date: Mon, 15 Dec 2025 15:21:21 +0300
Subject: [PATCH 3/4] Add get_random in walker scheme class

---
 src/rewriting_hw_1/walker_scheme.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/rewriting_hw_1/walker_scheme.py b/src/rewriting_hw_1/walker_scheme.py
index 16d8218..26ee8b4 100644
--- a/src/rewriting_hw_1/walker_scheme.py
+++ b/src/rewriting_hw_1/walker_scheme.py
@@ -1,3 +1,6 @@
+from math import floor
+
+
 class WalkerScheme:
     def __init__(self, events_and_probabilities: list[tuple[str, int]]):
         if sum(probability[1] for probability in events_and_probabilities) != 1:
@@ -67,7 +70,7 @@ def _get_table(self, events_and_probabilities):
 
         return table
 
-
-scheme = WalkerScheme([("A", 0.1), ("B", 0.5), ("C", 0.4)])
-
-print(scheme.table)
+    def get_random(self, probability):
+        if self.table[floor(probability * len(self.table))][2] > probability:
+            return self.table[floor(probability * len(self.table))][0]
+        return self.table[floor(probability * len(self.table))][1]

From 86396bac179d3314f0e379e2a838d56f4e50ec32 Mon Sep 17 00:00:00 2001
From: Nicholay Shestakov <nicholas.shestakov@gmail.com>
Date: Mon, 15 Dec 2025 15:23:54 +0300
Subject: [PATCH 4/4] Update walker scheme test

---
 tests/walker_scheme_test.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/walker_scheme_test.py b/tests/walker_scheme_test.py
index de1cdbf..41ab194 100644
--- a/tests/walker_scheme_test.py
+++ b/tests/walker_scheme_test.py
@@ -4,5 +4,6 @@
 def test_exception():
     try:
         scheme = WalkerScheme([("A", 0.1), ("B", 1)])
+        print(scheme)
     except Exception as e:
         assert str(e) == "Сумма вероятностей не равна 1."