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Return an iterator from std::lower_bound
/* Return an iterator from std::lower_bound */
#include <iostream>
using std::cout;
using std::endl;
#include <algorithm>
#include <vector>
#include <iterator>
int main()
{
int a1[ 10 ] = { 2, 2, 4, 4, 4, 6, 6, 6, 6, 8 };
std::vector< int > v( a1, a1 + 10 );
std::ostream_iterator< int > output( cout, " " );
std::copy( v.begin(), v.end(), output );
std::vector< int >::iterator lower;
lower = std::lower_bound( v.begin(), v.end(), 6 );
cout << ( lower - v.begin() );
return 0;
}
/*
2 2 4 4 4 6 6 6 6 8 5
*/
Return iterator to beginning. Returns an iterator pointing to the first element in the vector. Notice that, unlike member vector::front, which returns a reference to the first element, this function returns a random access iterator pointing to it. If the container is empty, the returned iterator value shall not be dereferenced. The C++ function std::vector::begin() returns a random access iterator pointing to the first element of the vector. This function does not accept any parameter.
Ostream iterators are output iterators that write sequentially to an output stream (such as cout). They are constructed from a basic_ostream object, to which they become associated, so that whenever an assignment operator (=) is used on the ostream_iterator (dereferenced or not) it inserts a new element into the stream. Optionally, a delimiter can be specified on construction. This delimiter is written to the stream after each element is inserted.
Iterators are just like pointers used to access the container elements. Iterators are one of the four pillars of the Standard Template Library or STL in C++. An iterator is used to point to the memory address of the STL container classes. For better understanding, you can relate them with a pointer, to some extent. Iterators act as a bridge that connects algorithms to STL containers and allows the modifications of the data present inside the container. They allow you to iterate over the container, access and assign the values, and run different operators over them, to get the desired result. • Iterators are used to traverse from one element to another element, a process is known as iterating through the container. • The main advantage of an iterator is to provide a common interface for all the containers type. • Iterators make the algorithm independent of the type of the container used.
copy() function is used to copy items from one iterator to another iterator with a specific range. We can define the start and end position of the source and it will copy all items in this rage to a different destination. To use copy() function, we need to include <bits/stdc+.h> or header file. It copies all the elements pointed by first and last. first element is included in the output but last is not. output is the start position of the final result iterator. It returns one iterator to the end of the destination range where elements have been copied. Function returns an iterator to the end of the destination range where elements have been copied.
Return iterator to end. Returns an iterator referring to the past-the-end element in the vector container. The past-the-end element is the theoretical element that would follow the last element in the vector. It does not point to any element, and thus shall not be dereferenced. Because the ranges used by functions of the standard library do not include the element pointed by their closing iterator, this function is often used in combination with vector::begin to specify a range including all the elements in the container. If the container is empty, this function returns the same as vector::begin. This function does not accept any parameter.
Put character. Inserts character c into the stream. Internally, the function accesses the output sequence by first constructing a sentry object. Then (if good), it inserts c into its associated stream buffer object as if calling its member function sputc, and finally destroys the sentry object before returning. Function returns the ostream object (*this).
#include is a way of including a standard or user-defined file in the program and is mostly written at the beginning of any C/C++ program. This directive is read by the preprocessor and orders it to insert the content of a user-defined or system header file into the following program. These files are mainly imported from an outside source into the current program. The process of importing such files that might be system-defined or user-defined is known as File Inclusion. This type of preprocessor directive tells the compiler to include a file in the source code program.
In C++, vectors are used to store elements of similar data types. However, unlike arrays, the size of a vector can grow dynamically. That is, we can change the size of the vector during the execution of a program as per our requirements. Vectors are part of the C++ Standard Template Library. To use vectors, we need to include the vector header file in our program. The vector class provides various methods to perform different operations on vectors. Add Elements to a Vector: To add a single element into a vector, we use the push_back() function. It inserts an element into the end of the vector. Access Elements of a Vector: In C++, we use the index number to access the vector elements. Here, we use the at() function to access the element from the specified index.
Return iterator to lower bound. Returns an iterator pointing to the first element in the range [first,last) which does not compare less than val. The elements are compared using operator< for the first version, and comp for the second. The elements in the range shall already be sorted according to this same criterion (operator< or comp), or at least partitioned with respect to val. The function optimizes the number of comparisons performed by comparing non-consecutive elements of the sorted range, which is specially efficient for random-access iterators. Unlike upper_bound, the value pointed by the iterator returned by this function may also be equivalent to val, and not only greater.
A program shall contain a global function named main, which is the designated start of the program in hosted environment. main() function is the entry point of any C++ program. It is the point at which execution of program is started. When a C++ program is executed, the execution control goes directly to the main() function. Every C++ program have a main() function.
Quick sort is based on an 'algorithmic' design pattern called 'divide-conquer'. Unlike Merge Sort it does not require 'extra memory space'. The average time complexity is "O(n*log(n))"
Algorithm takes the input of 'n' data element and prints all 'possible combination'. For that, it maintains a boolean 'Array of Length' "n". If the corresponding boolean value is true, then
