题目链接：zoj 3810 A Volcanic Island

题目大意：给定n，要求用n块面积为n的拼图铺满n?n的矩阵，任意两块拼图形状不能相同（包括旋转和镜像），并且n块拼图只能有4中颜色，相邻两块拼图颜色不能相同。

解题思路：构造，n = 2，3，4时是不存在的。然后对于n >= 5的直接构造，具体看代码。注意这种构造方式构造6的时候会出现相同的拼图，所以特判。

#include 
   
     #include 
    
      #include 
     
       using namespace std; const int maxn = 105; const char s[10][10] = {"BBBBBB", "GGRGRR", "GRRGRB", "GRGGRB", "GRGRRB", "GRGBBB"}; const char c[5] = "BGRY"; int g[maxn][maxn]; void solve (int n) { memset(g, 0, sizeof(g)); for (int i = 0; i < n; i++) g[0][i] = 3; int k = (n - 1) / 2, col = 1; for (int i = 0; i < k; i++) { for (int j = 1; j <= i+1; j++) g[j][i+1] = col; for (int j = i+1; j < n; j++) g[j][i] = col; col = 3 - col; } for (int i = k; i < n; i++) { for (int j = 2; j <= i+2; j++) g[j][i+2] = col; g[i+2][i+1] = col; for (int j = i+2; j < n; j++) g[j][i] = col; col = 3 - col; } for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) printf("%c", c[g[i][j]]); printf("\n"); } } int main () { int cas, n; scanf("%d", &cas); while (cas--) { scanf("%d", &n); if (n == 1) printf("B\n"); else if (n == 6) { for (int i = 0; i < 6; i++) printf("%s\n", s[i]); } else if (n >= 5) { solve(n); } else printf("No solution!\n"); } return 0; }