Notebook.md

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true	us-letter-light	true	Γα=Ω5 Notebook

Template

#pragma GCC optimization("Ofast")//-0.0+0.0=-0  
#pragma GCC optimization("unroll-loops")
#pragma GCC target ("avx2")
#include<bits/stdc++.h>

using ull = unsigned long long;
using ll = long long;
using namespace std;
#define endl '\n'
#define dbg(...) cerr<<"LINE("<<__LINE__<<")->["<<#__VA_ARGS__<<"]:<<(__VA_ARGS__);   
#define pb push_back 
#define F first
#define S second

int main(){
ios_base::sync_with_stdio(0);cin.tie(0);
//freopen("in.txt", "r", stdin);
    int tc=2;
    //cin>>tc;
    int n;
    while(tc--){
        cin>>n;
        for(int i=0;i<n;++i){
            //code
        }
    }
return 0;
}

---

Containers

Data types

(-10^9 to +10^9)

int: -2,147,483,648 to 2,147,483,647 unsigned int: 0 to 4,294,967,295

(-10^18 to +10^18)

long long: -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 unsigned long long: 0 to 18,446,744,073,709,551,615

(7 digit precision): float: 1,175494351 E - 38 to 3,402823466 E + 38

(15 digit precision): double: 2,2250738585072014 E - 308 to 1,7976931348623158 E + 308

---

Misc Math functions

min({a, b, c, d});  max({a, b, c, d});
bool flag; cout << (flag ? "YES" : "NO");//ternary op
numeric_limits<unsigned int>::max();  numeric_limits<float>::min();
cout << fixed << setprecision(digits)<< var;// digits == 0 ? (round)
round(num);//1.45 -> 1 , 1.5 -> 2
trunc(num);//1.5 -> 1 
ceil(num);//1.5 -> 2 
floor(num);//1.5 -> 1
abs(num);// -1.5 -> 1.5, 1.5 -> 1.5
sqrt(num);  sqrtl(num); 
pow(base, exp); powl(base,exp); pow(p, 1.0 / n);// nth root of p
var<<exp;//var*(2^exp)
var>>exp;//var/(2^exp)

First 25 primes

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97

Algorithms

bool isPrime(int n){
    if (n<2) return false;
    if (n<=3) return true;
    if (!(n%2) || !(n%3)) return false;
    for (int i=5;i*i<=n;i+=6)
        if (!(n%i) || !(n%(i+2))) return false;
    return true;
}

// global constants for fibonnacci
const double sqrt5 = sqrt(5);
const double phi = (1 + sqrt5) / 2;
const double psi = (1 - sqrt5) / 2;
ull fibonacci(int n) {//O(1) of the first 70 fib numbers
    return round( (pow(phi, n) - pow(psi, n)) / (sqrt5) );
}

Ciruclar Array

int dist1 = abs(idx1-idx2);         int dist2 = n - dist1;
for (int i = idx1; i != idx2; i = (i - 1 + n) % n) {}//Left
for (int i = idx1; i != idx2; i = (i + 1 + n) % n) {}//right

---

sorting

sort(vec.begin(), vec.end());//ascending
sort(vec.begin(), vec.end(), greater<int>());//non ascending

inline bool myOrder(pair<int, int> p1, pair<int, int> p2) {
    return p1.first < p2.first;
}
vector<pair<int, int>> vec = {{3, 1}, {2, 5}, {1, 4}};
sort(vec.begin(), vec.end(), myOrder);
for(auto elem : vec)
    cout << "(" << elem.first << ", " << elem.second << ") ";

Standard Template Library (STL)

Iterators

for(vector<int>::iterator it=stl.begin(); it!=stl.end(); it++)
    cout<<*it<<" ";//(it) is memory pointer (*it) its value     
for (const auto& pair : mapVar)
    cout << pair.first << ": " << pair.second;

Capacity:

stl.size(); //lenght of STL container
stl.empty(); // boolean function

Modifiers:

stl.clear();//clears the container but complexity O(n) better use swap(v,vv[i])
stl.erase(it);stl.erase(itBegin,itEnd);// removes elements from  range
stl.resize(size);stl.resize(size,initializer);stl.insert(it,elem)
stl.emplace_back(elem)//faster push_back (avoid copies), inmediate values

.fun()	.push_back(elem)	.pop_back()	.insert(elem)	.find(elem)
vector	x	x		find(v.beg(),v.end(),elem)
string	x	x	x
maps			(make_pair(e,e))	x
sets			(elem)	x

---

Operations

if (stl.find(elem) != stl.end())//found 
stl.count(elem);//count the occurrences of the element, sets and maps only

STL Algorithms

int sum = accumulate(v.begin(), v.end(), sumStart);
int product = accumulate(v.begin(), v.end(), 1,multiplies<int>());
merge(v1.begin(), v1.end(), v2.begin(), v2.end(), back_inserter(vecM));
fill(v.begin(), v.end(), value);iota(vec.begin(), vec.end(),start);
auto maxElement = max_element(vec.begin(), vec.end());
// use: cout << (maxElement != vec.end() ? *maxElement : “NO”);

strings

string substr1=str1.substr(start, end);
int found1 = str.find(substr1);//first find at
int found2 = str.find(substr1, found1 + 1);//second find at
if (found1 != string::npos) //found

str1.replace(start, str2.size(), str2);    
str1.erase(start, end);
str1.append(str2); str3 = str1 + str2;

char ch; 
isalpha(ch);isdigit(ch);isupper(ch);islower(ch);//char bools
tolower(ch);toupper(ch);//alphabet
char numC='1'; int  numI=numC-'0';//toInt 
int numI=1;   char numC=numI+'0';//toChar

std::stringstream ss;    ss << str1.substr(0, 1) << str1.substr(3, 4);

//circular string rotation 
string s;
vector<string> v1(s.size());
vector<string> v2(s.size());
for(int i=0;i<s.size();i++){
    v1[i] = s.substr(i,s.size()-i) + s.substr(0,i);//left
    v2[i] = s.substr(s.size()-i,i) + s.substr(0,s.size()-i);//right
}