What is lower_bound ()?
In C++, lower_bound is a function provided by the Standard Template Library (STL) that is used for binary searching in a sorted sequence. It is defined in the <algorithm> header and is typically used with containers like vectors, arrays, or other data structures that support random access.
lower_bound function is used to find the iterator pointing to the first element in a sorted sequence that is not less than a specified value. It is commonly used with sorted containers to quickly locate an element or determine the position where an element should be inserted while maintaining the sorted order.
Syntax of lower_bound:
template <class ForwardIterator, class T>
ForwardIterator lower_bound(ForwardIterator first, ForwardIterator last, const T& value);
- ‘first’ and ‘last’ are iterators defining the range in which you want to search for the value. and ‘value‘ is the value that you want to find or insert.
- The lower_bound function returns an iterator pointing to the first element in the range [first, last) that is not less than value. If no such element is found, it returns last.
GFact | Why s.lower_bound(x) is faster than lower_bound(s.begin(), s.end(), x) in C++ STL?
Have you ever got TLE on solving a question using function lower_bound (s.begin(), s.end(), x) and when you use s.lower_bound(x) it runs just fine (here s is a Data structure and x is the value we are searching for) !! If “Yes” then why this happens?
Well, we are going to find out this in the following article, but before that let’s know about the function, lower_bound () in C++, first.
Why s.lower_bound(x) is faster than lower_bound(s.begin(), s.end(), x) in C++ STL?