Min / Max

Compare two integers and get minimum or maximum using a built-in function.

int a = 7;
int b = 4;
int M = max(a, b) // 7
int m = min(a, b) // 4

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Swap

Use the built-in swap method to swap two variables of the same type.

int a = 5, b = 8;
swap(a, b);

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Auto

The auto keyword automatically derives the data type from the initialization so you don’t have to.

This is very handy at times when the data type is complex, like a vector of pair of integers

vector<pair<pair<int,int>,pair<int,int>>> v;

To iterate using a for loop we would do this:

for (pair<pair<int,int>,pair<int,int>> it : v)

Which can make the code unreadable and slow you down. The same happens when using the auto keyword.

for (auto it : v)

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Pair

Many times, pair is a handy alternative to defining struct or class.

Suppose you need a structure to define a point, meaning you need an x and a y coordinate.

Using a structure:

struct Point {
    int x;
    int y;
}

This can be simplified using pair.

There are multiple ways to initialize.

pair<int,int> coord = {x, y} 
pair<int,int> coord = make_pair(x, y) 

Access members using the first and second keyword:

pair<int,int> coord = {x, y} 
int x = coord.first
int y = coord.second

You can also use different data types for the first and second member and compose a pair inside a pair. For example:

pair<string, pair<int, int> > var = {"abc",{4, 5} }

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In the next lesson, we’ll discuss how input and output works in C++.