Advent2021/Day 4/Marcus/cpp/part1.cpp

#include <iostream>
#include <vector>
#include <cstring>

using namespace std;

struct board
{
    int nums[25];  
  
    friend istream &operator>>( istream  &input, board &b ) { 
        for(int i = 0; i < 25; i++) input >> b.nums[i];
        return input;
    }
    
    bool marked[25];
};

bool is_winning(board b);
int board_score(board b, int last_drawn);

int main()
{
    int drawing[100];
    
    vector<board> boards;
    board next_board;
    
    for(int i = 0; i < 100; i++) cin >> drawing[i];
    
    while (cin >> next_board)
    {
        memset(next_board.marked, false, 25);
        boards.push_back(next_board);
    }

    for(int i = 0; i < 100; i++)
    {
        for(int j = 0; j < boards.size(); j++)
        {
            for(int k = 0; k < 25; k++)
            {
                if (drawing[i] == boards[j].nums[k])
                {
                    boards[j].marked[k] = true;
                    if (is_winning(boards[j]))
                    {
                        cout << board_score(boards[j], drawing[i]) << endl;
                        return 0;
                    }
                }
            }
        }
    }

    return 0;
}

bool is_winning(board b)
{
    for(int i = 0; i < 5; i++)
    {
        if (b.marked[5*i] && b.marked[5*i+1] && b.marked[5*i+2] && b.marked[5*i+3] && b.marked[5*i+4])
        {
            return true;
        }
    }
    
    for(int i = 0; i < 5; i++)
    {
        if (b.marked[i] && b.marked[i+5] && b.marked[i+10] && b.marked[i+15] && b.marked[i+20])
        {
            return true;
        }
    }
    
    return false;
}

int board_score(board b, int last_drawn)
{
    int sum = 0;
    for(int i = 0; i < 25; i++)
    {
        if (!b.marked[i])
        {
            sum += b.nums[i];
        }
    }
    return last_drawn*sum;
}