stlDemo.cpp

#include <algorithm>
#include <deque>
#include <iostream>
#include <map>
#include <set>
#include <string>
#include <vector>
using namespace std;

bool f(int x, int y) { return x > y; }

// Note that all the operation is perform in O(logn)
void vector_demo() {
  std::vector<int> A = {11, 2, 5, 15, 3};
  std::cout << A[1] << std::endl;
  // sorting the vector it takes O(nlogn);
  sort(A.begin(), A.end()); // nlogn
  // use binary search to find wether an element is in it or not

  // O(nlogn)
  bool present = std::binary_search(A.begin(), A.end(), 3);
  for (int i = 0; i < A.size(); ++i) {
    std::cout << A[i] << " ";
  }
  std::cout << "\n" << std::endl;
  std::cout << present << std::endl; // return True

  A.push_back(50);
  A.push_back(100);
  A.push_back(100);
  A.push_back(100);
  A.push_back(120);
  A.push_back(125);
  std::cout << A[A.size() - 1] << std::endl;
  std::cout << A.capacity() << std::endl;
  std::cout << A.max_size() << std::endl;
  std::cout << A.empty() << std::endl;

  // using upper bound and lower bound
  std::vector<int>::iterator it = std::lower_bound(A.begin(), A.end(), 100);
  std::vector<int>::iterator it1 = std::upper_bound(A.begin(), A.end(), 100);
  std::cout << *it << std::endl;
  std::cout << *it1 << std::endl;
  // find the number of time 100 occurs in this std::vector<> ;
  int occurence = it1 - it;
  std::cout << "The number of times 100 occurs is: " << occurence << std::endl;
  // sorting the vector in asscending order
  sort(A.begin(), A.end(), f);
  // To print the sorted  vector
  std::cout << "The elements of the vector in asscending order is: "
            << std::endl;
  std::vector<int>::iterator it3;
  for (it3 = A.begin(); it3 != A.end(); it3++) {
    std::cout << *it3 << std::endl;
  }
  /* We can also perform the same traversal operation with using the following:
     we can change iterator to auto like this:
     - auto it = lower_bound(A.begin(), A.end(),100)
     - auto it1 = upper_bound(A.begin(), A.end(),100)
     Now the for loop will be:
     for(int &x:A) // reference
     {
     x++
     }
     for(int x :A){
     std::cout << x << std::endl;
     }
*/
}

// set demo
void setDemo() {
  std::set<int> s;
  s.insert(1);
  s.insert(-7);
  s.insert(5);
  s.insert(-2);
  s.insert(8);
  s.insert(9);
  for (int x : s) {
    std::cout << x << std::endl;
  }
  // to find if -2 is in the set
  auto it = s.find(-2);
  if (it == s.end()) {
    std::cout << "Not present" << std::endl;
  } else {
    std::cout << "Present" << std::endl;
    std::cout << *it << std::endl;
  }
  // now let's find all the element strictly greater than -2
  auto it2 = s.upper_bound(-2);
  auto it3 = s.lower_bound(5);
  std::cout << *it2 << " " << *it3 << std::endl;
  // Note: if we try to use upper_bound on something that doesn't exit then it
  // will go to end()
}

// map demo
void mapDemo() {
  std::map<int, int> A;
  A[1] = 100;
  A[2] = -1;
  A[1] = 10;
  std::cout << A[2] << std::endl;
  // we can do it for char also
  std::map<char, int> cnt;
  std::string x = "Abdoulaye Balde";
  for (char c : x) {
    std::cout << cnt['a'] << " " << cnt['z'] << std::endl;
  }
}

void find_in_dequeue() {
  deque<int> coll{2, 4, 6, 8, 19, -5};

  for (int i = 0; i < 10; i++) {
    auto result = std::find(coll.cbegin(), coll.cend(), i);
    if (result != coll.cend()) {
      cout << "Was found " << *result << "\n";
    } else {
      cout << "Was not found"
           << "\n";
    }
  }
}

int main(int argc, char *argv[]) {
  find_in_dequeue();
  return 0;
}