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

题目传送门

 /*
     题意：在n^n的海洋里是否有k块陆地
     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
                 输出完k个L后，之后全部输出S:)
     5 10 的例子可以是这样的：
     LSLSL
     SLSLS
     LSLSL
     SLSLS
     SSSSS
 */
 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <cmath>
 #include <string>
 using namespace std;

 const int MAXN = 1e2 + ;
 const int INF = 0x3f3f3f3f;

 int main(void)        //Codeforces Round #302 (Div. 2) B Sea and Islands
 {
     freopen ("B.in", "r", stdin);

     int n, k;
     while (scanf ("%d%d", &n, &k) == )
     {
         int mx = n * n / ;
         if ((n*n) & )    mx += ;
         if (k > mx)    puts ("NO");
         else
         {
             puts ("YES");
             if (k == )
             {
                 for (int i=; i<=n; ++i)
                 {
                     for (int j=; j<=n; ++j)    printf ("%c", 'S');
                     puts ("");
                 }
             }
             else
             {
                 int cnt = ;    bool flag = true;
                 for (int i=; i<=n; ++i)
                 {
                     for (int j=; j<=n; ++j)
                     {
                         if (flag)    {printf ("%c", 'L');    ++cnt;}
                         else    printf ("%c", 'S');
                         if (cnt == k)    flag = false;
                         else    flag = !flag;
                     }
                     if (n %  ==  && cnt < k)    flag = !flag;
                     puts ("");
                 }
             }
         }
     }

     return ;
 }

 /*
 YES
 SSSSS
 LLLLL
 SSSSS
 LLLLL
 SSSSS
 NO
 */