{"trustable":false,"prependHtml":"\u003cscript\u003e window.katexOptions \u003d { disable: true }; \u003c/script\u003e\n\u003cscript type\u003d\"text/x-mathjax-config\"\u003e\n MathJax.Hub.Config({\n tex2jax: {\n inlineMath: [[\u0027$$$\u0027,\u0027$$$\u0027], [\u0027$\u0027,\u0027$\u0027]],\n displayMath: [[\u0027$$$$$$\u0027,\u0027$$$$$$\u0027], [\u0027$$\u0027,\u0027$$\u0027]]\n }\n });\n\u003c/script\u003e\n\u003cscript async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\" type\u003d\"text/javascript\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"PLAIN","content":"[NWUACM] \n给出无向图中M个节点间N条边的权值。\n求一个使得所有点连通的子图,要求图内的边权和最小"}},{"title":"Input","value":{"format":"PLAIN","content":"测试输入包含若干测试用例\n每个测试用例的第1行包含N、M ( \u003c100 )\n随后的 N 行每行包含3个数,边的起点,终点,权值\n节点从1到M编号\n当N为0时,全部测试结束. \n\u003cbr\u003e"}},{"title":"Output","value":{"format":"PLAIN","content":"对每个测试用例,在1行里输出最小生成树权值。\n若不存在符合要求的子图,则输出“?”。 "}},{"title":"Sample Input","value":{"format":"PLAIN","content":"3 3\n1 2 1\n1 3 2\n2 3 4\n1 3\n2 3 2\n0 100"}},{"title":"Sample Output","value":{"format":"PLAIN","content":"3\n?"}}]}