ABC133 C - Remainder Minimization 2019

提出

WA/TLE

code: python

l, r = map(int,input().split())

nums = set()

ans = float('inf')

flag = True

for i in range(l, r+1):

if (flag):

for j in range(i+1, r+1):

res = (i * j) % 2019

if (res in nums):

flag = False

else:

nums.add(res)

if (res < ans):

ans = res

print(ans)

解答

code: python

l, r = map(int,input().split())

nums = set()

ans = float('inf')

for i in range(l, r):

for j in range(i+1, r+1):

res = (i * j) % 2019

if (res < ans):

ans = res

if (ans == 0):

print(0)

exit()

print(ans)

メモ

(x×y)mod2019 = ((xmod2019) × (ymod2019))mod2019

i % 2019をiを増やしながら考えていくと、最悪でも2019個以内に0になるものが存在する

解答

code: python

l, r = map(int, input().split())

# mod2019

# iが決まる -> i + 2019 or i + 1

# 短調増加