mbardauskas/cpp-notes

C++ notes for competetive programming

template for competetive programming

#include <bits/stdc++.h>
using namespace std;

int main() {
  // solution
}

compiling with C++11 standard, optimizing code and showing all warnings about possible errors

g++ -std=c++11 -O2 -Wall code.cpp -o bin

Input and output is sometimes a bottleneck. Snippet for more efficient code:

ios_base::sync_with_stdio(0);
cin.tie(0);

using files for input and output. Use the following inside the main file

freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);

using \n is faster because std::endl always causes flush operation

cout << a <<< "\n";

comparing floats

if (abs(a-b) < 1e-9) { // a and b are equal
}