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수학동아 - 폴리매스
원파
2020.12.20 09:00
조회 601
수학자 12번에서 막혀 있는 분들이 많던데요.
아주 간단히 풀 방법이 있습니다.
모든 순열을 다 해보려면 20! 가지의 경우를 계산해 보아야 합니다.
이는 약 2 * 10^18 가지이죠.
그리고, 각 순열마다 i, j를 모두 확인해보기 위해 약 20*20=400 가지가 곱해집니다.
그러면 총 가짓수는 8 * 10^20 가지 정도 되겠네요.
평범한 노트북에서(혹은 서버에서) C++은 대체로 1초에 10^8가지의 연산을 할 수 있다고 알려져 있습니다.
그러면, 8 * 10^12 초 정도 걸릴텐데, 실제로 컴파일을 하면 이보다 오래 걸리기 때문에, 10^13초 정도로 잡으셔도 됩니다.
그래서요?
1초에 10^21번의 연산을 할 수 있는(그 이상이면 더 좋고요) 슈퍼 컴퓨터 한 대면 충분합니다!
혹 슈퍼 컴퓨터가 집에 없다면, 평범한 노트북 10^13대만 있으면 됩니다!
얼마나 쉽습니까?!
이제 모든 폴매 분들께서 수학자 모드를 깨는 것은 뭐 하루도 안남은 사실이네요.
그럼 전 이만 가보겠습니당~
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원파
Lv.9
2020.12.21 08:27
좋아요0
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황금 열쇠
Lv.7
2020.12.21 20:41
간단하네요 누구나 집에 슈퍼 컴퓨터 한 대나 노트북 10^13개쯤은 있잖아요?
지금 바로
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