构造 Codeforces Round #302 (Div. 2) B Sea and Islands

 1 /*
 2     题意：在n^n的海洋里是否有k块陆地
 3     构造算法：按奇偶性来判断，k小于等于所有点数的一半，交叉输出L/S
 4                 输出完k个L后，之后全部输出S:)
 5     5 10 的例子可以是这样的：
 6     LSLSL
 7     SLSLS
 8     LSLSL
 9     SLSLS
10     SSSSS
11 */
12 #include <cstdio>
13 #include <cstring>
14 #include <algorithm>
15 #include <cmath>
16 #include <string>
17 using namespace std;
18 
19 const int MAXN = 1e2 + 10;
20 const int INF = 0x3f3f3f3f;
21 
22 int main(void)        //Codeforces Round #302 (Div. 2) B Sea and Islands
23 {
24     freopen ("B.in", "r", stdin);
25 
26     int n, k;
27     while (scanf ("%d%d", &n, &k) == 2)
28     {
29         int mx = n * n / 2;
30         if ((n*n) & 1)    mx += 1;
31         if (k > mx)    puts ("NO");
32         else
33         {
34             puts ("YES");
35             if (k == 0)
36             {
37                 for (int i=1; i<=n; ++i)
38                 {
39                     for (int j=1; j<=n; ++j)    printf ("%c", 'S');
40                     puts ("");
41                 }
42             }
43             else
44             {
45                 int cnt = 0;    bool flag = true;
46                 for (int i=1; i<=n; ++i)
47                 {
48                     for (int j=1; j<=n; ++j)
49                     {
50                         if (flag)    {printf ("%c", 'L');    ++cnt;}
51                         else    printf ("%c", 'S');
52                         if (cnt == k)    flag = false;
53                         else    flag = !flag;
54                     }
55                     if (n % 2 == 0 && cnt < k)    flag = !flag;
56                     puts ("");
57                 }
58             }
59         }
60     }
61 
62 
63     return 0;
64 }
65 
66 /*
67 YES
68 SSSSS
69 LLLLL
70 SSSSS
71 LLLLL
72 SSSSS
73 NO
74 */
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