闲来无聊，前两天看到一篇关于算法实现的文章。里面又关于图的各种算法介绍，正好上学期还学过图论，现在还记得一点点，先来实现个prim算法：
表示图的文件的内容大体上是这样的：
1 2.0 1.0 1.0 2 3.0 1.0 1.0 3 4.0 1.0 1.0 4 5.0 1.0 1.0 5 6.0 1.0 1.0 6 7.0 1.0 1.0 7 8.0 1.0 1.0 8 9.0 1.0 1.0 9 11.0 1.0 1.0 10 12.0 1.0 1.0 11 13.0 1.0 1.0 12 14.0 1.0 1.0 13 18.0 1.0 1.0 14 20.0 1.0 1.0 15 22.0 1.0 1.0 16 32.0 1.0 1.0 17 34.0 10.0 1.0 18 34.014.0 1.0 19 33.0 15.0 1.0 20 34.0 15.0 1.0 21 33.0 16.0 1.0 22 34.0 16.0 1.0 23 33.0 19.0 1.0 24 34.0 19.0 1.0 25 3.0 2.0 1.0 26 4.0 2.0 1.0 27 8.0 2.0 1.0 28 14.0 2.0 1.0 29 18.0 2.0 1.0 30 20.0 2.0 1.0 31 22.0 2.0 1.0 32 31.0 2.0 1.0 33 34.0 20.0 1.0 34 33.0 21.0 1.0 35 34.0 21.0 1.0 36 33.0 23.0 1.0 37 34.0 23.0 1.0 38 26.0 24.0 1.0 39 28.0 24.0 1.0 40 30.0 24.0 1.0 41 33.0 24.0 1.0 42 34.0 24.0 1.0 43 26.0 25.0 1.0 44 28.0 25.0 1.0 45 32.0 25.0 1.0 46 32.0 26.0 1.0 47 30.0 27.0 1.0 48 34.0 27.0 1.0 49 34.0 28.0 1.0 50 32.0 29.0 1.0 51 34.0 29.0 1.0 52 4.0 3.0 1.0 53 8.0 3.0 1.0 54 9.0 3.0 1.0 55 10.0 3.0 1.0 56 14.0 3.0 1.0 57 28.0 3.0 1.0 58 29.0 3.0 1.0 59 33.0 3.0 1.0 60 33.0 30.0 1.0 61 34.0 30.0 1.0 62 33.0 31.0 1.0 63 34.0 31.0 1.0 64 33.0 32.0 1.0 65 34.0 32.0 1.0 66 34.0 33.0 1.0 67 8.0 4.0 1.0 68 13.0 4.0 1.0 69 14.0 4.0 1.0 70 7.0 5.0 1.0 71 11.0 5.0 1.0 72 7.0 6.0 1.0 73 11.0 6.0 1.0 74 17.0 6.0 1.0 75 17.0 7.0 1.0 76 31.0 9.0 1.0 77 33.0 9.0 1.0 78 34.0 9.0 1.0