思维题 Gym 100553A Alter Board

题目传送门

 1 /*
 2     题意：一个n×m的矩形，相邻的颜色不同，黑或白。问最少的翻转次数，每次翻转可指定任意一个子矩形
 3     思维题：最少要把偶数行和列翻转，也就是n/2+m/2次
 4 */
 5 #include <cstdio>
 6 using namespace std;
 7
 8 int main(void)        //Gym 100553A Alter Board
 9 {
10 //    freopen ("A.in", "r", stdin);
11     freopen ("alter.in", "r", stdin);
12     freopen ("alter.out", "w", stdout);
13
14     int n, m;
15     while (scanf ("%d%d", &n, &m) == 2)
16     {
17         printf ("%d\n", n / 2 + m / 2);
18         for (int i=2; i<=n; i+=2)
19         {
20             printf ("%d %d %d %d\n", i, 1, i, m);
21         }
22         for (int i=2; i<=m; i+=2)
23         {
24             printf ("%d %d %d %d\n", 1, i, n, i);
25         }
26     }
27
28     return 0;
29 }