Project Euler Q19 - LO Man Hei

Download notebook

{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "ce0feff9-8e09-4427-b78c-c608946a9a9b",
   "metadata": {},
   "source": [
    "### Q19\n",
    "How many Sundays fell on the first of the month during the twentieth century (1 Jan 1901 to 31 Dec 2000)?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "9b2e4340-8c44-45ce-adeb-44ce64455df4",
   "metadata": {},
   "outputs": [],
   "source": [
    "month_days = {\n",
    "    \"normal\":{\n",
    "        1:31,  2:28,  3:31,  4:30,\n",
    "        5:31,  6:30,  7:31,  8:31,\n",
    "        9:30, 10:31, 11:30, 12:31\n",
    "    },\n",
    "    \"leap\":{\n",
    "        1:31,  2:29,  3:31,  4:30,\n",
    "        5:31,  6:30,  7:31,  8:31,\n",
    "        9:30, 10:31, 11:30, 12:31\n",
    "    }\n",
    "}\n",
    "\n",
    "def first_day_of_month(last_month_first_day, last_month, last_month_year):\n",
    "    year_type = \"normal\"\n",
    "    if (last_month_year%4 == 0 and last_month_year%100 != 0) or (last_month_year%400 == 0):\n",
    "        year_type = \"leap\"\n",
    "    first_day = (last_month_first_day+month_days[year_type][last_month])%7\n",
    "    month = last_month+1 if last_month < 12 else 1\n",
    "    year = last_month_year if last_month < 12 else last_month_year+1\n",
    "    return first_day,month,year\n",
    "\n",
    "def first_day_of_month_in_range(start_info, end_info):\n",
    "    # start_info = [day_of_first_day, month, year]\n",
    "    # end_info   = [month, year]\n",
    "    first_day_of_month_list = [start_info[0]]\n",
    "    iterating_info = start_info\n",
    "    while True:\n",
    "        iterating_info = first_day_of_month(iterating_info[0],iterating_info[1],iterating_info[2])\n",
    "        if ((iterating_info[2] > end_info[1]) or \n",
    "            (iterating_info[2] == end_info[1] and iterating_info[1] > end_info[0])):\n",
    "            break\n",
    "        first_day_of_month_list.append(iterating_info[0])\n",
    "    return first_day_of_month_list"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "58a4d119-c3c1-41e7-b577-9b2a60dc654d",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "CPU times: user 243 µs, sys: 63 µs, total: 306 µs\n",
      "Wall time: 307 µs\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "171"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "%%time\n",
    "(first_day_of_month_in_range([1,1,1900],[12,2000]).count(0) \n",
    " - first_day_of_month_in_range([1,1,1900],[12,1900]).count(0))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "3de13c29-0552-4834-ab26-540ef4a6d16e",
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3 (ipykernel)",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.8.10"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 5
}

Loading