Spaced Out

Problem

This problem is Spaced Out, Problem 3 from the USACO 2021 January Silver contest.

Solution

1#include <iostream>
2#include <algorithm>
3using namespace std;
4
5int main()
6{
7    int n;
8    cin >> n;
9    int grid[1000][1000];
10    for (int i = 0; i < n; i++)
11    {
12        for (int j = 0; j < n; j++)
13        {
14            cin >> grid[i][j];
15        }
16    }
17
18    int rows_alternate = 0, cols_alternate = 0;
19    // each row has an alternating pattern of cow and no cow
20    for (int i = 0; i < n; i++)
21    {
22        int sum[2]{};
23        // there are two ways to alternate, odd index and even index
24        for (int j = 0; j < n; j++)
25        {
26            sum[j % 2] += grid[i][j];
27        }
28        // add the best way to the answer for alternating rows
29        rows_alternate += max(sum[0], sum[1]);
30    }
31
32    // each column has an alternating pattern of cow and no cow
33    for (int i = 0; i < n; i++)
34    {
35        int sum[2]{};
36        // two ways to alternate
37        for (int j = 0; j < n; j++)
38        {
39            sum[j % 2] += grid[j][i];
40        }
41        // add the best way to the answer for alternating columns
42        cols_alternate += max(sum[0], sum[1]);
43    }
44
45    cout << max(rows_alternate, cols_alternate) << endl;
46    return 0;
47}

1#include <iostream>
2#include <algorithm>
3using namespace std;
4
5int main()
6{
7    int n;
8    cin >> n;
9    int grid[1000][1000];
10    for (int i = 0; i < n; i++)
11    {
12        for (int j = 0; j < n; j++)
13        {
14            cin >> grid[i][j];
15        }
16    }
17
18    int rows_alternate = 0, cols_alternate = 0;
19    // each row has an alternating pattern of cow and no cow
20    for (int i = 0; i < n; i++)
21    {
22        int sum[2]{};
23        // there are two ways to alternate, odd index and even index
24        for (int j = 0; j < n; j++)
25        {
26            sum[j % 2] += grid[i][j];
27        }
28        // add the best way to the answer for alternating rows
29        rows_alternate += max(sum[0], sum[1]);
30    }
31
32    // each column has an alternating pattern of cow and no cow
33    for (int i = 0; i < n; i++)
34    {
35        int sum[2]{};
36        // two ways to alternate
37        for (int j = 0; j < n; j++)
38        {
39            sum[j % 2] += grid[j][i];
40        }
41        // add the best way to the answer for alternating columns
42        cols_alternate += max(sum[0], sum[1]);
43    }
44
45    cout << max(rows_alternate, cols_alternate) << endl;
46    return 0;
47}