nt size="3"><span style="color: black; font-family: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">给定一个网格的描述，输出最少需要多少条不构成环的蛇来覆盖这个网格。如果不存在能够覆盖网格的方案，输出</span><span lang="EN-US" style="color: black; font-family: Consolas; mso-bidi-font-family: Consolas">-1</span><span style="color: black; font-family: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-fa