altrko's blog

find function on set/multiset
By altrko, history, 3 weeks ago, In English

how to make find function on set/multiset correspond to last element of that kind? like on multiset with elements 1 7 7 7 8 9 i want iterator pointing on last 7 on index 3.

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3 weeks ago, # |
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Just use upper_bound and then decrement the iterator once.

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    3 weeks ago, # ^ |
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    Thanks so does lower_bound and find function do thr same thing?

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      3 weeks ago, # ^ |
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      Nah, they both are different thing.

      But you can always check that, if your iterator is pointing towards the correct element you want to find.

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        3 weeks ago, # ^ |
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        I dont get how are they different

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          3 weeks ago, # ^ |
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          Just search it on internet and you will get everything about it

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          2 weeks ago, # ^ |
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          lower_bound returns an iterator to the smallest element that is at least $$$x$$$.
          upper_bound returns an iterator to the smallest element that is greater than $$$x$$$.

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            2 weeks ago, # ^ |
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            i meant difference between lower_bound and find function

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              2 weeks ago, # ^ |
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              Imagine a set s of $$${1, 3, 5, 7}$$$. The followings will hold true:

              • s.find(4) == s.end()
              • s.lower_bound(4) == s.find(5)

              Hope that was clear.

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                2 weeks ago, # ^ |
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                so do u mean because 4 is not in the set it points to nothing?

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    3 weeks ago, # ^ |
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    wow, how did I not know you could use upper_bound on sets

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      2 weeks ago, # ^ |
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      yeah you can use it on sets and multisets but you have to use it like this st.upper_bound(x)

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3 weeks ago, # |
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auto it = st.upper_bound(number);

if (it != st.begin())
    it--;

in this way the iterator pointing on last occurrence of the number and if the condition is false or the value in the iterator not equal the number then the number doesn't exist

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