Week 9 Lab Exercise Solutions

ex1.cpp

#include <iostream>
#include <vector>

using namespace std;

void remove(vector<int>&, int);
void print(const vector<int>&);

int main() {
  vector<int> v;
  v.push_back(3);
  v.push_back(1);
  v.push_back(4);
  v.push_back(1);
  v.push_back(5);
  v.push_back(9);

  cout << "Before: ";
  print(v);

  cout << endl << "Remove element at index: ";
  int index = 0;
  cin >> index;
  remove(v, index);

  cout << "After: ";
  print(v);
  cout << endl;

  return 0;
}

void remove(vector<int> & v, int index) {
  int temp = 0;
  for (int i = index; i < v.size() - 1; ++i) {
    temp = v.at(i);
    v.at(i) = v.at(i + 1);
    v.at(i + 1) = temp;
  }
  v.pop_back();
}

void print(const vector<int> & v) {
  for (int i = 0; i < v.size(); ++i) 
    cout << v.at(i) << " ";
}

ex2.cpp

#include <iostream>
#include <vector>

using namespace std;

void print_freq(vector<int> & v) {
  for (int i = 0; i < v.size(); ++i) 
    cout << i + 1 << ": " << v[i] << endl;
}

int main() {
  vector<int> freq(10, 0);

  int next = 0;
  while (cin >> next) {
    freq.at(next - 1) = freq.at(next - 1) + 1;
  }

  print_freq(freq);
  
  return 0;
}

ex3.cpp

#include <iostream>
#include <vector>

using namespace std;

void print_board(const vector< vector<char> > &);

int main() {
  vector< vector<char> > outer;
  vector<char> inner(8, '-');
  
  for (int i = 0; i < 8; ++i)
    outer.push_back(inner);

  // initialize starting chess positions 
  outer.at(0).at(0) = 'R';
  outer.at(0).at(1) = 'H';
  outer.at(0).at(2) = 'B';
  outer.at(0).at(3) = 'Q';
  outer.at(0).at(4) = 'K';
  outer.at(0).at(5) = 'B';
  outer.at(0).at(6) = 'H';
  outer.at(0).at(7) = 'R';

  outer.at(7).at(0) = 'R';
  outer.at(7).at(1) = 'H';
  outer.at(7).at(2) = 'B';
  outer.at(7).at(3) = 'Q';
  outer.at(7).at(4) = 'K';
  outer.at(7).at(5) = 'B';
  outer.at(7).at(6) = 'H';
  outer.at(7).at(7) = 'R';

  for (int i = 0; i < 8; ++i) {
    outer.at(1).at(i) = 'P';
    outer.at(6).at(i) = 'P';
  }

  // run the game infinitely, ctrl-c to stop 
  int x1, y1, x2, y2;
  while (true) {
    print_board(outer);

    cout << "Move piece from location: ";
    cin >> x1 >> y1;
    cout << "To location: ";
    cin >> x2 >> y2;

    outer.at(outer.size() - y2 - 1).at(x2) = outer.at(outer.size() - y1 - 1).at(x1);
    outer.at(outer.size() - y1 - 1).at(x1) = '-';
  }
  
  return 0;
}

void print_board(const vector< vector<char> > & board) {
  for (int i = 0; i < board.size(); ++i) {
    for (int j = 0; j < board.at(i).size(); ++j) {
      cout << board.at(i).at(j) << " ";
    }
    cout << endl;
  }
}