tgbaodeeptry's blog

How can I check if (a + b) is larger than (max long long)
By tgbaodeeptry, history, 4 years ago, In English

Assume I have 3 long long varables a, b and n. And them are approximately (max long long)( 2.10^18 ).

So, are there any ways that I can check if a + b is larger than n?

Thanks so much guys

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4 years ago, # |
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Yes. Since a + b > n means a > n - b you can just check that.

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4 years ago, # |
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Convert them all to double.

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4 years ago, # |
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__builtin_add_overflow

https://wandbox.org/permlink/b6sxtBCF7900G74N

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4 years ago, # |
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ive seen people use logs like log(a) + log(b) >= 18 or something along those lines. personally I just ll overflow each time so I don't use it

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    4 years ago, # ^ |
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    Thats for multiplication I guess.

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