Tutorial : STL Pair timer 2s memory 1024MB

In two dimensions, the coordinates of all integer points are represented as ordered pairs in the form of (x, y).

How should we create many such points?

We could make a structure containing two int variables, but we can also manage them using the pair data type that we will learn about this time.

The pair data type is in the #include <utility> header. Let’s also use using namespace std;

(The utility header is often included inside <algorithm>, so adding only the <algorithm> header also works.)

It is declared as pair<data type, data type>.

If it is like the coordinates of an integer point (integer, integer), it would be pair<int, int>.

If you want an ordered pair of (string, integer), you declare it as pair<string, int>.

There are several ways to declare a pair and assign values to it, as shown below.

pair<int, int> a;

a = {2, 5};  // ①

a = make_pair(2, 5); // ②

a.first = 2; 
a.second = 5; // ③

Like method 1, you can assign values by enclosing them in braces,

or like method 2, you can use the make_pair function,

or like method 3, you can assign values to each element separately.

Here, the first element becomes (pair variable name).first, and the second element becomes (pair variable name).second. This is syntax, so you need to memorize it.

What happens if we sort a data structure containing multiple pairs?

Unless we explicitly set a different sorting standard,

it is designed to sort based on the first (front element) by default,

and among those with the same first (front element) value, it sorts based on the second (back element).

Now let’s solve a simple practice problem that applies this.