| layout | title |
|---|---|
../../layouts/CheatSheet.astro |
Cpp STL Cheatsheet |
Cpp Stl is a library of container classes, algorithms, and iterators. It is a generalized library and so, its components are parameterized. C++ STL is a set of C++ template classes to provide common programming data structures and functions such as lists, stacks, arrays, etc. It is a library of container classes, algorithms, and iterators. It is a generalized library and so, its components are parameterized. C++ STL is a set of C++ template classes to provide common programming data structures and functions such as lists, stacks, arrays, etc.
// Vector initialization
vector<int> v;
// Vector Insetion element
cout << "Insertion of element in vector: " << endl;
cout << endl;
for (int i = 0; i < n; i++)
{
v.push_back(a[i]);
}
// Vector Display element
cout << "Display element of vector " << endl;
for (int i = 0; i < n; i++)
{
cout << v[i] << " ";
}
cout << endl;
// // Vector maximum element
int maximum = *max_element(v.begin(), v.end());
// Vector minimum element
int minimum = *min_element(v.begin(), v.end());
cout << "Maximum element in vector " << maximum << endl;
cout << "Minmum element in vector " << minimum << endl;
sort(v.begin(), v.end());
// Vector sort element
cout << "Sort element of vector " << endl;
for (int i = 0; i < n; i++)
{
cout << v[i] << " ";
}
reverse(v.begin(), v.end());
cout << endl;
// Vector reverse element
cout << "Reverse element of vector " << minimum << endl;
for (int i = 0; i < n; i++)
{
cout << v[i] << " ";
}
cout << endl;
// Vector deletion
cout << "Delete last element of vector " << endl;
v.pop_back();
for (int i = 0; i < n; i++)
{
cout << v[i] << " ";
} // Set initialization
set<int> s;
cout << endl;
// Set insertion
cout << "Insertion in set " << endl;
cout << endl;
for (int i = 0; i < n; i++)
{
s.insert(a[i]);
}
// Set display
cout << "Display of set element" << endl;
for (auto i = s.begin(); i != s.end(); i++)
{
cout << *i << " ";
}
//Unordered Set initialization
unordered_set<int> s1;
cout << endl;
// unordered set insertion
cout << "Insertion in unordered set " << endl;
for (int i = 0; i < n; i++)
{
s1.insert(a[i]);
}
// Unordered set display
cout << "Display of unordered set element" << endl;
for (auto i = s1.begin(); i != s1.end(); i++)
{
cout << *i << " ";
} // Map initialization
map<int, int> m;
cout << endl;
// Map insertion
cout << "Insertion in map " << endl;
for (int i = 0; i < n; i++)
{
m[a[i]]++;
}
cout << "Display of map element" << endl;
// map display
for (auto i = m.begin(); i != m.end(); i++)
{
cout << i->first << " " << i->second << endl;
} // Unordered_Map initialization
unordered_map<int, int> um;
cout << endl;
// Unordered_Map insertion
cout << "Insertion in Unordered_Map " << endl;
for (int i = 0; i < n; i++)
{
um[a[i]]++;
}
cout << "Display of map element" << endl;
// Unordered_Map display
for (auto i = um.begin(); i != um.end(); i++)
{
cout << i->first << " " << i->second << endl;
} // Stack initialization
stack<int> st;
cout << endl;
// Stack insertion
cout << "Insertion in stack " << endl;
for (int i = 0; i < n; i++)
{
st.push(a[i]);
}
// Stack display
cout << "Display and removal of stack element" << endl;
for (auto i = s.begin(); i != s.end(); i++)
{
cout << st.top() << " ";
st.pop();
} // Queue initialization
queue<int> q;
cout << endl;
// Queue insertion
cout << "Insertion in queue " << endl;
for (int i = 0; i < n; i++)
{
q.push(a[i]);
}
// Queue display
cout << "Display of queue element" << endl;
for (auto i = s.begin(); i != s.end(); i++)
{
cout << q.front() << " ";
q.pop();
}
// Deque initialization
deque<int> d;
// Deque insertion
cout << "Insertion in deqeue " << endl;
for (int i = 0; i < n; i++)
{
d.push_front(a[i]);
}
cout << "Display of dequeue element" << endl;
// Deque display
for (auto i = s.begin(); i != s.end(); i++)
{
cout << d.front() << " ";
d.pop_back();
}
cout << "Deletion of dequeue element" << endl;
d.pop_back();
// Vector pair initialization
vector<pair<int, int>> p;
// Vector pair insertion
cout << "Insertion in vector pair " << endl;
cout << endl;
for (int i = 0; i < n; i++)
{
p.push_back({a[i], i});
}
// Vector pair Display
cout << "Display of vector pair element" << endl;
for (auto i = 0; i < v.size(); i++)
{
cout << p[i].first << " " << p[i].second << endl;
}
cout << endl; list <int> LI;
list <int>::iterator it;
//inserts elements at end of list
LI.push_back(4);
//inserts elements at beginning of list
LI.push_front(3);
//returns reference to first element of list
it = LI.begin();
//inserts 1 before first element of list
LI.insert(it,1);
//list traversal
for(it = LI.begin();it!=LI.end();it++)
{
cout<<*it<<" ";
}
cout<<endl;
//reverse elements of list
LI.reverse();
//removes all occurences of 5 from list
LI.remove(5);
//removes last element from list
LI.pop_back();
//removes first element from list
LI.pop_front(); priority_queue<int> pq;
// priority queue insertion
pq.push(10);
pq.push(20);
// priority queue display
while (!pq.empty()) {
cout << '\t' << g.top();
g.pop();
}
cout << '\n';
cout << "\n size if pq : " << pq.size();
cout << "\n top element of pq : " << pq.top();
// priority queue deletion
pq.pop();Hidden Functions
__gcd(value1, value2)
// Return gcd of two numbers, without using Euclidean Algorithm
__builtin_ffs(x)
//This function returns 1 + position of least significant 1-bit of x. Here x is int, this function with suffix 'l' gets
//a long argument and with suffix 'll' gets a long long argument.
e.g. __builtin_ffs(10) = 2 because 10 is '...10 1 0' in base 2 and first 1-bit from right is at index 1 (0-based) and
function returns 1 + index.
__builtin_clz(x)
//This function returns number of leading 0-bits of x which starts from most significant bit position. x is unsigned int. If
//this function with suffix 'l gets a unsigned long argument and with suffix 'll' gets a unsigned long long argument. If x =
//= 0, returns an undefined value.
e.g. __builtin_clz(16) = 27 because 16 is ' ... 10000' in base-2. Number of bits in a unsigned int is 32. so function
returns 32 — 5 = 27.
__builtin_ctz(x)
//This function returns number of trailing 0-bits of x which starts from least significant bit position. x is unsigned int and
//like previous function this function with suffix 'l' gets a unsigned long argument and with suffix 'll' gets a unsigned long
//long argument. If x == 0, returns an undefined value.
e.g. __builtin_ctz(16) = 4 because 16 is '...1 0000 '. Number of trailing 0-bits is 4.
__builtin_popcount(x)
//This function returns number of 1-bits of x. x is unsigned int and like previous function this function with suffix 'l' gets
//a unsigned long argument and with suffix 'll' gets a unsigned long long argument. If x == 0, returns an undefined value.
e.g. __builtin_popcount(14) = 3 because 14 is '... 111 0' and has three 1-bits.
__builtin_parity(x)
//This function returns 1 if number of 1-bits of x is odd, otherwise returns 0. x is unsigned int and like previous function
binary_search(arr, arr + n, key)
// This function returns true if key is present in arr[0..n-1]. Else it returns false.It is a built-in function for binary search in C++.
lower_bound(arr, arr + n, key)
// This function returns an iterator pointing to the first element in the range [first,last) which has a value not less than ‘val’.
upper_bound(arr, arr + n, key)
// This function returns an iterator pointing to the first element in the range [first,last) which has a value greater than ‘val’.
next_permutation(arr, arr + n)
// This function returns true if the next permutation of the sequence is possible. Else it returns false. It is a built-in function for next permutation in C++.
prev_permutation(arr, arr + n)
// This function returns true if the previous permutation of the sequence is possible. Else it returns false. It is a built-in function for previous permutation in C++.