AGC008 A - Simple Calculator

備忘録

問題

atcoder.jp

回答

import sys
import os
import math
import bisect
import itertools
import collections
import heapq
import queue
import array
import time


# 時々使う
# import numpy as np
# from decimal import Decimal, ROUND_HALF_UP
# from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall
# from collections import defaultdict, deque

# 再帰の制限設定
sys.setrecursionlimit(10000000)


def ii(): return int(sys.stdin.buffer.readline().rstrip())
def il(): return list(map(int, sys.stdin.buffer.readline().split()))
def fl(): return list(map(float, sys.stdin.buffer.readline().split()))
def iln(n): return [int(sys.stdin.buffer.readline().rstrip())
                    for _ in range(n)]


def iss(): return sys.stdin.buffer.readline().decode().rstrip()
def sl(): return list(map(str, sys.stdin.buffer.readline().decode().split()))
def isn(n): return [sys.stdin.buffer.readline().decode().rstrip()
                    for _ in range(n)]


def lcm(x, y): return (x * y) // math.gcd(x, y)


# MOD = 10 ** 9 + 7
MOD = 998244353
INF = float('inf')


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")

    x, y = il()
    if x == y:
        print(0)
        exit()

    if x > 0 and y > 0:
        if x > y:
            print(abs(x-y)+2)
        else:
            print(abs(x-y))
    elif x < 0 and y < 0:
        if x > y:
            print(abs(x-y)+2)
        else:
            print(abs(x-y))
    elif x > 0 and y < 0:
        y *= -1
        print(abs(x-y)+1)
    elif x < 0 and y > 0:
        x *= -1
        print(abs(x-y)+1)
    elif x < 0 and y == 0:
        print(abs(x))
    elif x > 0 and y == 0:
        print(x + 1)
    elif x == 0 and y < 0:
        y *= -1
        print(abs(x-y)+1)
    elif x == 0 and y > 0:
        print(y)


if __name__ == '__main__':
    main()

考え方

上記の回答例は、取りうるパターンをとりあえず全て書いて通した愚直実装。
しかしながら、押すボタンのパターンはA, BA, AB, BABの4パターンだけなので、
これらについて網羅する下記のような回答がバグも起き辛く良い。

def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")
 
    x, y = il()
    ret = 10**10
    if x <= y:
        # A
        ret = min(ret, y-x)
    if -x <= y:
        # BA
        ret = min(ret, y+x+1)
    if y <= x:
        # BAB
        ret = min(ret, x-y+2)
    if -y >= x:
        # AB
        ret = min(ret, -y-x+1)
    print(ret)