{"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":"HTML","content":"\u003cscript type\u003d\u0027text/x-mathjax-config\u0027\u003eMathJax.Hub.Config({tex2jax: { inlineMath: [[\u0027$\u0027,\u0027$\u0027]] } }); \u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027 src\u003d\u0027https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\u0027\u003e\u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027\u003esetTimeout(function(){MathJax.Hub.Queue([\u0027Typeset\u0027, MathJax.Hub, \u0027left_view\u0027]);}, 2000);\u003c/script\u003e\n\u003cdiv class\u003d\"panel_content\"\u003e \n中北大学acm数学专场专场中有这样一个问题\n 给你一组数w1,w2,w3......wn\n再给你一组数x1,x2,x3......xn,且x[i]\u003d1或-1;\n那么你知道∑(w[i]-x[i]*a)^2最小是多少吗?(a\u003e0)"}},{"title":"Input","value":{"format":"HTML","content":"第一行输入一个数T代表将有T组测试数据。\n对下面每组数据\n第一行输入一个数N(1\u0026lt;\u003dn\u0026lt;\u003d \u003cspan\u003e\u003cspan\u003e\u003cspan\u003e10^5)\n第二行输入n个数w1,w2,w3......wn(-10^4\u0026lt;\u003dwi\u0026lt;\u003d\u003cspan\u003e\u003cspan\u003e\u003cspan\u003e10^4)."}},{"title":"Output","value":{"format":"HTML","content":"对每组测试样例来说,以分数的形式输出∑(w[i]-x[i]*a)^2的最小值,如p/q,q\u003e0。"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cpre\u003e3\n4\n1 2 3 4\n4\n2 2 2 2\n5\n5 6 2 3 4\u003c/pre\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cpre\u003e5/1\n0/1\n10/1\u003c/pre\u003e"}}]}