Is there a TreeSet data structure equivalent in C++ with similar functions

Question

I need to use a Tree Set data structure(available in java) in C++, and make use of functions like TreeSet.lower(i) and TreeSet.higher(i) - > which returns the element just lower, and just higher than i in the given tree set. Is there an STL?

Edit: Following is the functionality I need, I was wondering how to use the upper_bound and lower_bound functions to do it:

for (int i = 1; i<10; i++) myset.insert(i * 10); // 10 20 30 40 50 60 70 80 90
int k = 50;  // I need 40 and 60
set<int>::iterator itr = myset.find(k);

if (itr != myset.end()) {
    // Found the element
    itr--; // Previous element;
    cout << *(itr); //prints 40
    itr++; // the element found
    itr++; // The next element
    cout << *(itr);  // prints 60
}

score 13 · Accepted Answer · answered Apr 28 '18 at 15:48

Use std::set, which is typically implemented as a binary search tree.

Its insert(), erase() and find() methods are logarithmic in size, but can do better if a hint is given. The logarithmic complexity is reffered to the the Java TreeSet.

I think you should be interested in std::lower_bound, which returns an iterator to the lower bound, and in std::upper_bound, which returns an iterator to the upper bound.

score 2 · Answer 2 · answered Apr 28 '18 at 15:47

2

You can use std::set
Look at std::set::lower_bound and std::set::upper_bound

answered Apr 28 '18 at 15:47

Daniel

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std::set is perfect for this situation. Thanks @dani – Batwoman05 Apr 28 '18 at 17:48

score 2 · Answer 3 · answered Sep 03 '20 at 17:37

You can use std::set here. And for your functionality you can use functions upper_bound(i) and lower_bound(i) but catch here is they don't work similar to TreeSet.lower(i) and TreeSet.higher(i).

lower_bound(const i) – Returns An iterator to the the first element in the container which is not considered to go before i (i.e., either it is equivalent or goes after), or set::end if all elements are considered to go before i.

upper_bound(const i) – Returns an iterator to the first element in the container which is considered to go after i, or set::end if no elements are considered to go after i.

for (int i = 1; i<10; i++) myset.insert(i * 10); // 10 20 30 40 50 60 70 80 90
int k = 50; 
set<int>::iterator itlow,itup;

itlow=myset.lower_bound (k);  
itup=myset.upper_bound (k);

if(itlow!=myset.begin()){
   itlow--;
   cout << *itlow;  // 40 will print
}
cout << *itup;  // 60 will print

Is there a TreeSet data structure equivalent in C++ with similar functions

3 Answers3