upper_bound in C++
upper_bound() is a standard library function in C++ defined in the header
ForwardIterator upper_bound (ForwardIterator first, ForwardIterator last, const T& val);
ForwardIterator upper_bound (ForwardIterator first, ForwardIterator last, const T& val, Compare comp);
first, last: The range used is [first, last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.
val: Value of the upper bound to search for in the range.
comp: Binary function that accepts two arguments (the first of the type pointed by ForwardIterator, and the second, always val), and returns a value convertible to bool. The function shall not modify any of its arguments. This can either be a function pointer
or a function object.
Return type : An iterator to the upper bound of val in the range. If all the element in the range compare less than val, the function returns last.
Input : 10 20 30 30 40 50 Output : upper_bound for element 30 is at index 4 Input : 10 20 30 40 50 Output : upper_bound for element 45 is at index 4 Input : 10 20 30 40 50 Output : upper_bound for element 60 is at index 5
Below are some C++ programs to illustrate the use of std::upper_bound :
Vector contains : 10 20 30 40 50 upper_bound for element 35 is at position : 3 upper_bound for element 45 is at position : 4
Array contains : 10 20 30 40 50 upper_bound for element 35 is at position : 3 upper_bound for element 45 is at position : 4
Time Complexity : The number of comparisons performed is logarithmic in the distance between first and last. i.e, (at most log2(last – first) + O(1) comparisons).
- std::upper_bound() returns an iterator to the upper bound of the value passed to it.
- std::upper_bound() works only with sorted sequences. i.e. vector with sorted elements or array with sorted elements.
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