Submission #77049

#	Time	Username	Problem	Language	Result	Execution time	Memory
77049		antimirage	Chessboard (IZhO18_chessboard)	C++17	0 / 100	35 ms	1312 KiB

chessboard

#include <bits/stdc++.h>

using namespace std;

const int N = 1e5 + 5;

int n, k, x[2][N], y[2][N];

long long ans = 1e18;

long long calc (int i)
{
    long long res = 0;

    for (int j = 1; j <= k; j++)
    {
        if ((x[0][j] / i + y[0][j] / i) & 1)
            res++;
    }
    return min( res + (n * 1ll * n + 1) / 2 - (k - res), (k - res) + (n * 1ll * n) / 2  - res);
}

int main()
{
    cin >> n >> k;

    for (int i = 1; i <= k; i++)
    {
        scanf("%d%d", &x[0][i], &y[0][i]), x[0][i]--, y[0][i]--;
        scanf("%d%d", &x[1][i], &y[1][i]), x[1][i]--, y[1][i]--;
    }
    for (int i = 1; i * i <= n; i++)
    {
        if (n % i != 0) continue;

        ans = min(ans, calc(i) );
        ans = min(ans, calc(n / i) );
    }
    cout << ans << endl;
}
/**
6 8
3 3 3 3
1 2 1 2
3 4 3 4
5 5 5 5
4 3 4 3
4 4 4 4
2 1 2 1
3 6 3 6

4 1
4 1 4 4
**/

Compilation message (stderr)

chessboard.cpp: In function 'int main()':
chessboard.cpp:29:53: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &x[0][i], &y[0][i]), x[0][i]--, y[0][i]--;
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
chessboard.cpp:30:53: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &x[1][i], &y[1][i]), x[1][i]--, y[1][i]--;
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~

• Subtask 1: 0 / 8
• Subtask 2: 0 / 8
• Subtask 3: 0 / 15
• Subtask 4: 0 / 16
• Subtask 5: 0 / 23
• Subtask 6: 0 / 30