Dice simulator

.gitignore

@@ -1,2 +1,3 @@
 .idea
 .venv
+*.build

Uebung-01/decomposition.py

@@ -0,0 +1,14 @@
+import math
+
+def decomp(x: int, base: list[int]) -> dict[int, int]:
+    base = sorted(base, reverse=True)
+
+    coef = {}
+    for b in base:
+        c = math.floor(x / b)
+        coef[b] = c
+        x -= b * c
+
+    return coef
+
+print(decomp(25, [1, 5, 10, 25]))

Uebung-01/perseverance.py

@@ -10,28 +10,34 @@ max_y = len(data)
 max_x = len(data[0])
 start = (max_y-1, max_x-1)
 
-# Cache with size of n points
+# Table with size of data
-cache = [[None for _ in range(max_x)] for _ in range(max_y)]
+table = [[None for _ in range(max_x)] for _ in range(max_y)]
 
 def find_path(y, x):
+    # Return bad value for positions which are out of bounds
     if not (0 <= y < max_y and 0 <= x < max_x):
         return (), float('-inf')
 
-    if cache[y][x] is not None:
+    # Table look up
-        return cache[y][x]
+    if table[y][x] is not None:
+        return table[y][x]
 
+    # End of the recursion is the starting position
     if y == 0 and x == 0:
         res = (((y, x),), data[y][x])
+    # Calculate defined recursion on all other existing positions
     else:
         west_path, west_val = find_path(y, x-1)
         north_path, north_val = find_path(y-1, x)
 
+        # Choose most valuable path to the considered position
         if west_val > north_val:
             res = (west_path + ((y, x),), west_val + data[y][x])
         else:
             res = (north_path + ((y, x),), north_val + data[y][x])
 
-    cache[y][x] = res
+    # Store most valuable path in the table and return
+    table[y][x] = res
     return res
 
 path, val = find_path(*start)

Uebung-02/dice.cpp

@@ -0,0 +1,60 @@
+#include <pybind11/pybind11.h>
+#include <pybind11/stl.h>
+#include <random>
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+class Dice {
+    std::vector<std::string> sides;
+    std::vector<double> probs;
+    std::mt19937 gen;
+    std::discrete_distribution<> dist;
+
+public:
+    size_t accepted = 0;
+    size_t rejected = 0;
+
+    Dice(const std::vector<std::string>& sides, const std::vector<double>& probs)
+        : sides(sides), probs(probs), gen(std::random_device{}()), dist(probs.begin(), probs.end()) {}
+
+    std::string fair_dice() {
+        while (true) {
+            std::vector<std::string> res;
+            for (size_t i = 0; i < sides.size(); ++i)
+                res.push_back(sides[dist(gen)]);
+            std::set<std::string> uniq(res.begin(), res.end());
+            if (uniq.size() == res.size()) {
+                ++accepted;
+                return res[0];
+            }
+            ++rejected;
+        }
+    }
+
+    std::map<std::string,int> throw_dice(int n) {
+        std::map<std::string,int> res;
+        for (auto& s : sides) res[s] = 0;
+        for (int i = 0; i < n; ++i)
+            res[fair_dice()]++;
+        return res;
+    }
+
+    std::pair<size_t,size_t> stats() const { return {accepted, rejected}; }
+
+    void reset_stats() { accepted = rejected = 0; }
+};
+
+namespace py = pybind11;
+
+PYBIND11_MODULE(dice, m) {
+    py::class_<Dice>(m, "Dice")
+        .def(py::init<const std::vector<std::string>&, const std::vector<double>&>())
+        .def("fair_dice", &Dice::fair_dice)
+        .def("throw_dice", &Dice::throw_dice)
+        .def("stats", &Dice::stats)
+        .def("reset_stats", &Dice::reset_stats)
+        .def_readwrite("accepted", &Dice::accepted)
+        .def_readwrite("rejected", &Dice::rejected);
+}

Uebung-02/dice.py

@@ -0,0 +1,36 @@
+from lib.Natives import NativeLoader
+
+def throw_dice_cpp(n: int, sides: list, probs: list):
+    loader = NativeLoader()
+    dice_mod = loader.cpp("dice")
+    Dice = dice_mod.Dice
+    d = Dice(sides, probs)
+    d.reset_stats()
+    res = d.throw_dice(n)
+    accepted, rejected = d.stats()
+    return res, accepted, rejected
+
+
+dice_sides = ['1', '2', '3', '4', '5', '6']
+dice_props = [0.1, 0.1, 0.1, 0.1, 0.1, 0.5]
+
+coin_sides = ['Head', 'Number']
+coin_head = [0.1, 0.5]
+
+rep = 100000
+
+# --- Dice test ---
+res_cpp, acc_dice, rej_dice = throw_dice_cpp(rep, dice_sides, dice_props)
+total = sum(res_cpp.values())
+probs_estimated = {k: v / total for k, v in res_cpp.items()}
+print("C++ Dice result (relative):", probs_estimated)
+print(f"Accepted: {acc_dice/(acc_dice+rej_dice)*100:.2f}%, "
+      f"Rejected: {rej_dice/(acc_dice+rej_dice)*100:.2f}%\n")
+
+# --- Coin test ---
+res_coin, acc_coin, rej_coin = throw_dice_cpp(rep, coin_sides, coin_head)
+total_coin = sum(res_coin.values())
+probs_coin = {k: v / total_coin for k, v in res_coin.items()}
+print("C++ Coin result (relative):", probs_coin)
+print(f"Accepted: {acc_coin/(acc_coin+rej_coin)*100:.2f}%, "
+      f"Rejected: {rej_coin/(acc_coin+rej_coin)*100:.2f}%")

Uebung-02/minsearch.py

@@ -0,0 +1,27 @@
+import random
+
+numsTest = [1, 2, 3, 4, 5]
+
+def search_min(nums):
+    if len(nums) == 1:
+        return nums[0]
+
+    num = nums[0]
+    nums.remove(num)
+
+    # n-1 recursions
+    rec_num = search_min(nums)
+
+    if rec_num < num:
+        return rec_num
+    else:
+        # n-1 times called in worst case
+        smaller = True
+        for n in nums:
+            if n <= num:
+                smaller = False
+        print('Hit')
+        assert smaller == True
+        return num
+
+print(search_min(numsTest))

lib/Natives.py

@@ -0,0 +1,159 @@
+import ctypes
+import pathlib
+import subprocess
+import hashlib
+import json
+import platform
+import sys
+import importlib.util
+import sysconfig
+import shutil
+from datetime import datetime
+from typing import Callable, Any, Tuple
+
+class LazyCall:
+    def __init__(self, func: Callable[..., Any], args: Tuple[Any, ...]) -> None:
+        self.func = func
+        self.args = args
+
+    # Calls C function lazily and returns string
+    def to_str(self) -> str:
+        self.func.restype = ctypes.c_char_p
+        res = self.func(*self.__convert_args())
+        return res.decode() if res else ""
+
+    # Calls C function lazily and returns int
+    def to_int(self) -> int:
+        self.func.restype = ctypes.c_int
+        return self.func(*self.__convert_args())
+
+    # Calls C function lazily and returns float
+    def to_float(self) -> float:
+        self.func.restype = ctypes.c_double
+        return self.func(*self.__convert_args())
+
+    # Convert arguments to C types
+    def __convert_args(self):
+        out = []
+        for a in self.args:
+            if isinstance(a, str):
+                out.append(ctypes.c_char_p(a.encode()))
+            elif isinstance(a, int):
+                out.append(ctypes.c_int(a))
+            elif isinstance(a, float):
+                out.append(ctypes.c_double(a))
+            else:
+                out.append(a)
+        return out
+
+
+class FunctionWrapper:
+    def __init__(self, lib: ctypes.CDLL, name: str) -> None:
+        self._lib = lib
+        self._name = name
+
+    # Prepares lazy function calls
+    def __call__(self, *args) -> LazyCall:
+        func = getattr(self._lib, self._name)
+        return LazyCall(func, args)
+
+
+class LibWrapper:
+    def __init__(self, lib: ctypes.CDLL) -> None:
+        self._lib = lib
+
+    # Exposes all C functions within the lib
+    def __getattr__(self, name: str) -> FunctionWrapper:
+        return FunctionWrapper(self._lib, name)
+
+
+class NativeLoader:
+    def __init__(self) -> None:
+        self.build_dir = pathlib.Path(".build")
+        self.build_dir.mkdir(exist_ok=True)
+        self.ext_suffix = sysconfig.get_config_var("EXT_SUFFIX") or sysconfig.get_config_var("SO")
+
+    # Loads a Cpp class
+    def cpp(self, path: str):
+        src = pathlib.Path(path).with_suffix(".cpp")
+        if not src.exists():
+            raise FileNotFoundError(src)
+        out = self.build_dir / f"{src.stem}_cpp"
+
+        if self.__needs_rebuild(src, out):
+            target = self.__build_cpp(src, out)
+        else:
+            target = str(out) + ".so"
+
+        spec = importlib.util.spec_from_file_location(src.stem, target)
+        mod = importlib.util.module_from_spec(spec)
+        sys.modules[src.stem] = mod
+        spec.loader.exec_module(mod)
+        return mod
+
+    # Loads a C lib
+    def c(self, path: str) -> LibWrapper:
+        src = pathlib.Path(path).with_suffix(".c")
+        if not src.exists():
+            raise FileNotFoundError(src)
+        out = self.build_dir / f"{src.stem}_c.so"
+        if self.__needs_rebuild(src, out):
+            self.__build_c(src, out)
+        lib = ctypes.CDLL(str(out))
+        return LibWrapper(lib)
+
+    @staticmethod
+    def __create_hash(path: pathlib.Path) -> str:
+        h = hashlib.sha256()
+        with open(path, "rb") as f:
+            for chunk in iter(lambda: f.read(8192), b""):
+                h.update(chunk)
+        return h.hexdigest()
+
+    @staticmethod
+    def __info_path(target: pathlib.Path) -> pathlib.Path:
+        return target.with_suffix(target.suffix + ".buildinfo")
+
+    @staticmethod
+    def __load_info(info_path: pathlib.Path):
+        if info_path.exists():
+            with open(info_path, "r") as f:
+                return json.load(f)
+        return None
+
+    def __write_info(self, info_path: pathlib.Path, src: pathlib.Path, out: pathlib.Path) -> None:
+        data = {
+            "os": platform.system(),
+            "build_date": datetime.now().isoformat(),
+            "src": str(src),
+            "out": str(out),
+            "src_hash": self.__create_hash(src),
+        }
+        with open(info_path, "w") as f:
+            json.dump(data, f, indent=2)
+
+    def __needs_rebuild(self, src: pathlib.Path, out: pathlib.Path) -> bool:
+        info = self.__load_info(self.__info_path(out))
+        final_out = pathlib.Path(str(out) + ".so")
+        if not info or not final_out.exists():
+            return True
+        try:
+            return info.get("src_hash") != self.__create_hash(src)
+        except FileNotFoundError:
+            return True
+
+    def __build_cpp(self, src: pathlib.Path, out: pathlib.Path) -> str:
+        includes = (subprocess.check_output(["python3", "-m", "pybind11", "--includes"]).decode().strip().split())
+
+        built_temp = str(out) + self.ext_suffix
+        final_path = str(out) + ".so"
+
+        subprocess.run(["c++", "-O3", "-shared", "-fPIC", "-std=c++17", *includes, str(src), "-o", built_temp], check=True)
+
+        shutil.move(built_temp, final_path)
+        self.__write_info(self.__info_path(out), src, out)
+        return final_path
+
+    def __build_c(self, src: pathlib.Path, out: pathlib.Path) -> None:
+        subprocess.run(["gcc", "-O3", "-shared", "-fPIC", "-std=c11", str(src), "-o", str(out)], check=True)
+        self.__write_info(self.__info_path(out), src, out)

requirements.txt

@@ -0,0 +1,3 @@
+pybind11>=2.12
+setuptools>=70.0
+wheel>=0.44