STL Algorithms

Sorting algorithm

The sorting algorithm is characterized by sorting the contents of containers in different ways, such as Sort().

function	algorithm
binary_search(first, last, val)	Binary search
equal_range(first, last, val)	Determine equality and return to an interval
includes(first, last, first2, last2)	Containment and
lexicographical_compare(first, last, first2, last2)	Comparisons in Dictionary Sorting
lower_bound(first, last, val)	lower limit
make_heap(first, last)	Making a heap
max(val1, val2)	Maximum
max_element(first, last)	Location of maximum value
merge(first, last, first2, last2, result)	Merge two sequences
min(val1, val2)	minimum value
min_element(first, last)	Location of minimum value
next_permutation(first, last)	Get the next permutation combination
nth_element(first, nth, last)	Rearrange the left and right ends of the nth element in a column
partial_sort_copy(first, last, first2, last2)	Locally sort and copy to other locations
partial_sort(first, middle, last)	Local sorting
pop_heap(first, last)	Extract an element from the heap
prev_permutation(first, last)	Change the order of elements within the first and last specified ranges of iterators so that the new permutation is the next one smaller than the original permutation. Another version of this function takes predicates as the third argument.
push_heap(first, last)	Press an element into heap
set_difference(first, last, first2, last2, result)	Get the previous permutation combination
set_intersection(first, last, first2, last2, result)	intersection
set_symmetric_difference(first, last, first2, last2, result)	Difference set
set_union(first, last, first2, last2, result)	combine
sort(first, last)	sort
sort_heap(first, last)	Sort heap
stable_sort(first, last)	Sort and keep the relative order of the equivalent elements
upper_bound(first, last, val)	Upper limit

sort(first, last)

Sort the elements within the scope specified by iterators first and last. Another version of this function takes predicates as the third parameter.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

void Test_sort()
{
	vector<int> int_vector;
	for (size_t i = 0; i < 10; i++) int_vector.push_back(i);
	random_shuffle(int_vector.begin(), int_vector.end());

	cout << "Vector:";
	for (int item : int_vector) cout << item << ' ';
	cout << endl;

	sort(int_vector.begin(), int_vector.end());

	cout << "Vector:";
	for (int item : int_vector) cout << item << ' ';
	cout << endl;
}

Output
Vector:8 1 9 2 0 5 7 3 4 6 Vector:0 1 2 3 4 5 6 7 8 9

partial_sort(first, middle, last)

Sort the elements within the scope specified by iterator first and last. Place the first part of the sequence (the range specified by first and middle) and the remaining elements in the latter part (the range specified by middle and last). Another version of this function takes the predicate as the fourth argument.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

void Test_partial_sort()
{
	vector<int> int_vector;
	for (size_t i = 0; i < 10; i++) int_vector.push_back(i);
	random_shuffle(int_vector.begin(), int_vector.end());

	cout << "Vector:";
	for (int item : int_vector) cout << item << ' ';
	cout << endl;

	// Replace only the first five elements after sorting
	partial_sort(int_vector.begin(), int_vector.begin() + 5, int_vector.end());

	cout << "Vector:";
	for (int item : int_vector) cout << item << ' ';
	cout << endl;
}

Output
Vector:8 1 9 2 0 5 7 3 4 6 Vector:0 1 2 3 4 9 8 7 5 6

nth_element(first, nth, last)

Find val in the sorted elements of the iterator first and last specified ranges. If an element with value is found, true is returned, otherwise false is returned. Another version of this function takes the predicate as the fourth argument.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

void Test_nth_element()
{
	vector<int> int_vector;
	for (size_t i = 0; i < 50; i++) int_vector.push_back(i);
	random_shuffle(int_vector.begin(), int_vector.end());

	cout << "Vector:";
	for (int item : int_vector) cout << item << ' ';
	cout << endl;

	nth_element(int_vector.begin(), int_vector.begin() + 5, int_vector.end());

	cout << "Vector:";
	for (int item : int_vector) cout << item << ' ';
	cout << endl;
}

Output
Vector:34 49 17 26 21 44 35 32 20 33 41 19 48 45 3 5 6 22 14 13 23 29 39 28 46 8 2 10 25 36 4 38 27 9 7 40 1 31 47 18 11 37 24 30 0 15 12 16 42 43 Vector:0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 41 33 32 40 44 49 47 34 46 37 39 35 45 36 48 38 42 43

merge(first, last, first2, last2, result)

The sorted elements in the first to last specified range are merged with the sorted elements in the first and last specified ranges, and the reordered elements are placed in the sequence starting from result. Another version of this function takes the predicate as the sixth argument.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

void Test_merge()
{
	vector<int> int_vector;
	for (size_t i = 0; i < 10; i++) int_vector.push_back(rand());
	sort(int_vector.begin(), int_vector.end());
	vector<int> int_vector2;
	for (size_t i = 0; i < 10; i++) int_vector2.push_back(rand());
	sort(int_vector2.begin(), int_vector2.end());

	cout << "Vector1:";
	for (int item : int_vector) cout << item << ' ';
	cout << endl;
	cout << "Vector2:";
	for (int item : int_vector2) cout << item << ' ';
	cout << endl;

	vector<int> result(int_vector.size() + int_vector2.size());
	// Merge must be a sorted sequence
	merge(int_vector.begin(), int_vector.end(), int_vector2.begin(), int_vector2.end(), result.begin());

	cout << "Vector3:";
	for (int item : result) cout << item << ' ';
	cout << endl;
}

Output
Vector1:41 6334 11478 15724 18467 19169 24464 26500 26962 29358 Vector2:491 2995 4827 5436 5705 9961 11942 16827 23281 28145 Vector3:41 491 2995 4827 5436 5705 6334 9961 11478 11942 15724 16827 18467 19169 23281 24464 26500 26962 28145 29358

includes(first, last, first2, last2)

Within the range specified by iterators first and last, if there is a sorted sequence with ranges specified by first and last 2, the true value is returned. Another version of this function takes the predicate as the fifth argument.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

void Test_includes()
{
	vector<int> int_vector{ 2,5,12,1,53,13,23,21,3,6,7,8,8 };
	sort(int_vector.begin(), int_vector.end());

	vector<int> int_vector2{ 8,6,7,8 };
	sort(int_vector2.begin(), int_vector2.end());

	cout << "Vector:";
	for (int item : int_vector) cout << item << ' ';
	cout << endl;

	cout << "Does it include:[6,7,8,8]" << endl;

	// Must be a sorted sequence
	bool is_includes = includes(int_vector.begin(), int_vector.end(), int_vector2.begin(), int_vector2.end());
	cout << "Result:" << (is_includes ? "Contain" : "Not included");
}

Output
Vector:1 2 3 5 6 7 8 8 12 13 21 23 53 Does it include: [6, 7, 8, 8] Result: Contains