{"id":1661,"date":"2020-03-19T15:42:00","date_gmt":"2020-03-19T07:42:00","guid":{"rendered":"http:\/\/www.shuizilong.com\/house\/?p=1661"},"modified":"2020-07-23T12:00:00","modified_gmt":"2020-07-23T04:00:00","slug":"uoj-87-mx-%e7%9a%84%e4%bb%99%e4%ba%ba%e6%8e%8c","status":"publish","type":"post","link":"https:\/\/www.shuizilong.com\/house\/archives\/uoj-87-mx-%e7%9a%84%e4%bb%99%e4%ba%ba%e6%8e%8c\/","title":{"rendered":"UOJ 87. mx \u7684\u4ed9\u4eba\u638c"},"content":{"rendered":"

\u53c2\u8003\u8d44\u6599<\/h1>\n

\u2013 \u5b98\u65b9\u9898\u89e3<\/a>
\n\u2013 https:\/\/blog.bill.moe\/uoj87-mxcactus\/<\/a><\/p>\n

\u9898\u610f<\/h1>\n

\u7ed9\u5b9a\u4e00\u4e2a\u4ed9\u4eba\u638c\uff0c\u6bcf\u6b21\u4ece\u4e2d\u9009\u53d6\u51e0\u4e2a\u5173\u952e\u8282\u70b9\uff0c\u6c42\u5b83\u4eec\u4e4b\u95f4\u4e24\u4e24\u4e4b\u95f4\u8ddd\u79bb\u7684\u6700\u5927\u503c\u3002<\/p>\n

\u9898\u89e3<\/h1>\n

\n \u5bf9\u4e8e\u6811\u7684\u60c5\u51b5\uff0c\u5982\u679c\u4f60\u53ea\u4f1a\u865a\u6811\u6216\u8005\u6811\u5206\u6cbb\uff0c\u5bf9\u4e8e\u4ed9\u4eba\u638c\u4f60\u80af\u5b9a\u4e5f\u53ea\u80fd\u8fd9\u4e48\u505a\u4e86\u3002
\n \u2014\u2014 \u5b98\u65b9\u9898\u89e3\n<\/p><\/blockquote>\n

\u6240\u4ee5\u8fd9\u4e2a\u9898\u4e43\u4f1a\u51e0\u79cd\u505a\u6cd5\uff0c\u53d6\u51b3\u4e8e\u6811\u7684\u7248\u672c\u7684\u90a3\u4e2a\u95ee\u9898\uff0c\u4f60\u4f1a\u51e0\u79cd\u505a\u6cd5\u3002\u5b98\u65b9\u9898\u89e3 \u7684\u516d\u3001\u4e03\u3001\u516b\u3001\u4e5d\uff0c\u63d0\u4f9b\u4e86\u56db\u79cd\u601d\u8def\u3002\u8fd9\u91cc\u5148\u5b9e\u73b0\u7b2c\u4e00\u4e2a\u7b97\u6cd5 \u2014\u2014 \u865a\u4ed9\u4eba\u638c\u3002<\/p>\n

\u865a\u6811<\/h2>\n

\u5148\u5f53\u6210\u6811\u505a\uff0c\u62ff\u4e2a 30 \u5206\u518d\u8bf4\u3002\u3002\u3002\u8fd9\u91cc\u6211\u7528 f[] \u6570\u7ec4\u8bb0\u5f55\u5411\u4e0b\u7684\u6700\u957f\u8ddd\u79bb\uff0c\u7136\u540e\u5728\u66f4\u65b0 f[u] \u4e4b\u524d\uff0c\u5148\u7528 f[v] \u548c f[u] \u4e00\u8d77\u66f4\u65b0\u4e00\u4e0b\u5168\u5c40\u7684\u76f4\u5f84\uff0c\u8fd9\u6837\u5c31\u4e0d\u9700\u8981\u8bb0\u5f55\u6b21\u5927\u503c\u4e86\uff01<\/p>\n

http:\/\/uoj.ac\/submission\/387435<\/a><\/p>\n

\u865a\u4ed9\u4eba\u638c (a.k.a. \u5706\u65b9\u6811)<\/h2>\n

\u9996\u5148\u5bf9\u8fd9\u7c7b\u9898\u76ee\u6765\u8bf4\uff0c\u901a\u5e38\u7684\u505a\u6cd5\uff0c\u662f dfs \u7684\u65f6\u5019\uff0c\u627e\u5230\u73af\uff0c\u7136\u540e\u518d\u73af\u4e0a\u624b\u5de5 dp \u4e00\u6b21\uff08\u4f46\u5176\u5b9e\u6211\u603b\u662f\u6572\u9519\uff0c\u9700\u8981\u4f9d\u9760\u5e95\u529b\uff09\uff0c\u628a\u7ecf\u8fc7\u73af\u7684\u7ed3\u679c\u7edf\u8ba1\u5230\u7b54\u6848\uff0c\u5e76\u66f4\u65b0\u5230\u73af\u4e0a\u7684\u6839\u8282\u70b9\u3002
\n\u4e8b\u5b9e\u4e0a\u5bf9\u4e8e BZOJ 1023. [SHOI2008]cactus\u4ed9\u4eba\u638c\u56fe<\/a> \u548c IOI 2008 D2T1 Islands<\/a> \u6211\u4eec\u5c31\u662f\u8fd9\u6837\u505a\u7684\uff08\u5206\u522b\u662f \u76f4\u5f84 \u548c \u6700\u957f\u94fe\uff0c\u8f6c\u79fb\u65b9\u7a0b\u51e0\u4e4e\u4e00\u6837\uff09\u3002<\/p>\n

\u4f46\u6211\u4eec\u53d1\u73b0\u5e76\u4e0d\u662f\u603b\u80fd\u9760\u5e95\u529b\u51f9\u51fa\u6765\uff0c\u6bd4\u5982 BZOJ 2125: \u6700\u77ed\u8def<\/a>\uff0c\u6811\u4e0a\u4e24\u70b9\u7684\u6700\u77ed\u8def\u9700\u8981\u6c42 lca\uff0c\u4ed9\u4eba\u638c\u4e0a\u600e\u4e48\u6c42 lca\uff0c\u4f3c\u4e4e\u9700\u8981\u5927\u91cf if-else \u5224\u65ad = =\uff01\uff01\uff01
\n\u8fd9\u4e2a\u9898\u7684\u60c5\u51b5\u7c7b\u4f3c\uff0c\u56e0\u4e3a\u5728\u6784\u5efa\u865a\u6811\u7684\u8fc7\u7a0b\u4e2d\uff0c\u6211\u4eec\u4e5f\u9700\u8981\u6c42 lca\u3002<\/p>\n

\u8fd9\u4e2a\u65f6\u5019\u6211\u4eec\u5c31\u9700\u8981\u4f7f\u7528\u4e00\u79cd \u5e38\u7528\u7684\u6280\u5de7 \u5706\u65b9\u6811\u3002\u53c2\u89c1 \u5706\u65b9\u6811\u2014\u2014\u5904\u7406\u4ed9\u4eba\u638c\u7684\u5229\u5668<\/a>\u3002<\/p>\n

\u7b80\u5355\u8bf4\u6765\uff0c\u5706\u65b9\u6811\u5c31\u662f\u628a\u73af\u8fb9\u90fd\u53bb\u6389\uff0c\u65b0\u5efa\u4e00\u4e2a \u65b9\u70b9 \u6765\u4ee3\u66ff\u8fd9\u4e2a\u73af\uff0c\u7528\u73af\u4e0a\u7684\u6839\u8282\u70b9\u8fde\u4e00\u6761\u8fb9\u5230\u5979\uff0c\u5728\u4ece\u5979\u5230\u6bcf\u4e2a\u73af\u4e0a\u7684\u5176\u4ed6\u8282\u70b9\u8fde\u4e00\u6761\u8fb9\uff0c\u5f62\u6210\u83ca\u82b1\u5f62\u72b6\u4ee5\u62c6\u73af\u4e3a\u6811\uff08\u600e\u4e48\u6837\uff1f\u662f\u4e0d\u662f\u5f88\u50cf block-cut tree<\/a>\uff09\u3002<\/p>\n

\u5177\u4f53\u5b9e\u4f5c\u7684\u8bdd\uff0c\u5148\u5efa\u4e09\u4e2a\u7ed3\u6784\u4f53\uff0c\u5206\u8868\u8868\u793a \u2014\u2014 \u539f\u56fe\uff0c\u5706\u65b9\u6811\uff0c\u865a\u6811\u3002\u5206\u522b\u8bb0\u4f5c G\uff0cC\uff0cT\u3002\u6c42\u5706\u65b9\u6811\u7684\u8fc7\u7a0b\uff0c\u53ef\u4ee5\u7c7b\u6bd4 tarjan \u6c42\u53cc\u8054\u901a\u5206\u91cf\uff0c\u6211\u8fd9\u8fb9\u662f\u5728\u6700\u6df1\u7684\u8282\u70b9\u62c9\u56de\u53cd\u5411\u8fb9\u7684\u65f6\u5019\uff0c\u628a\u73af\u62a0\u51fa\u6765\u7684\uff08\u56e0\u800c\u9700\u8981\u53d6\u4e2a\u53cd\uff09\u3002
\n\u8fd9\u91cc\u8fde\u5411\u65b9\u70b9\u7684\u6743\u503c\u4e3a 0\uff0c\u800c\u4ece\u65b9\u70b9\u8fde\u51fa\u7684\u8fb9\u7684\u6743\u503c\u4e3a\u5de6\u53f3\u4e24\u6761\u8def\u5f84\u7684\u957f\u5ea6\u53d6 min\u3002<\/p>\n

\u7d27\u63a5\u7740\u5728 C \u4e0a\u518d dfs \u4e00\u6b21\uff0c\u9884\u5904\u7406\u51fa dp \u548c lca \u6240\u9700\u8981\u7684\u4fe1\u606f\uff0c\u4e3a\u6784\u9020\u865a\u6811\u505a\u51c6\u5907\u3002\u6700\u540e\u6c42\u865a\u6811\u7684\u5730\u65b9\uff0c\u548c \u4e4b\u524d\u5199\u7684\u4ee3\u7801 \u552f\u4e00\u7684\u4e0d\u540c\uff0c\u662f\u5982\u679c\u662f\u4ece\u65b9\u70b9\u8fde\u51fa\u53bb\u7684\u8fb9\uff0c\u9700\u8981\u628a\u8fd9\u4e2a\u73af\u4e0a\u8fde\u51fa\u53bb\u7684\u90a3\u4e2a\u5b69\u5b50\u4e5f\u52a0\u5230\u6811\u4e2d\uff0c\u56e0\u4e3a\u6211\u4eec\u9700\u8981\u8fd9\u4e9b\u8282\u70b9\u6765\u6b63\u786e\u5904\u7406\u73af\u4e0a\u7684 DP\u3002<\/p>\n

\nvoid add_edge(int x, int y) {\nif (x &gt; G.n &amp;&amp; x != C.fa[0][y]) { \/\/ \u5982\u679c\u662f\u4ece\u65b9\u70b9\u8fde\u51fa\u53bb\uff0c\u5e76\u4e14 y \u4e0d\u662f\u8fde\u51fa\u53bb\u7684\u90a3\u4e2a\u5b69\u5b50\u3002\nint z = C.move_up(y, C.dep[y]-C.dep[x]-1);\nadj[x].PB(z);\nx = z;\n}\nadj[x].PB(y);\n}\n<\/pre>\n
\u8fd9\u4e2a\u5730\u65b9\u4e5f\u662f\u4e4b\u524d\u88f8\u51f9\u7684\u65f6\u5019\u6700\u9ebb\u70e6\u7684\u5730\u65b9\uff0c\u56e0\u4e3a\u73b0\u5728\u6709\u4e86\u5706\u65b9\u6811\uff0c\u6240\u4ee5\u51e0\u884c\u5c31\u5904\u7406\u4e86\u6389\u4e86w\u3002<\/p>\n
\u63a5\u4e0b\u6765\u662f\u4e0b\u4e00\u4e2a\u5bb9\u6613\u9519\u7684\u5730\u65b9\uff0c\u4ee5\u6837\u4f8b\u6765\u8bf4\uff0c\u5728\u5efa\u7acb\u865a\u6811\u7684\u65f6\u5019\u6211\u4eec\u4f1a\u628a 2 \u548c 9 \u6240\u5728\u7684\u8fd9\u4e2a\u73af\u4e5f\u52a0\u5230\u865a\u6811\u91cc\uff0c\u800c\u8fd9\u4e2a\u73af\u672c\u8eab\u7684\u4fe1\u606f\u6709\u53ef\u80fd\u4f1a\u8282\u5916\u751f\u679d\uff0c\u5305\u542b\u4e00\u4e9b\u672c\u4e0d\u5e94\u8be5\u88ab\u8003\u8651\u5230\u8282\u70b9\uff08\u8fd9\u91cc\u662f 7\uff09\uff0c\u6240\u4ee5\u6211\u4eec\u66f4\u65b0\u7b54\u6848\u7684\u65f6\u5019\u5e72\u8106\u53ea\u7528\u5706\u70b9\u7684\u4fe1\u606f\u66f4\u65b0\u5373\u53ef\uff08\u4e0a\u9762 add_edge \u91cc\u8865\u4e0a\u7684\u8282\u70b9\u5e76\u4e0d\u4f1a\u5f71\u54cd\uff09\u3002<\/p>\n
\u53c2\u89c1 \u4e0b\u56fe<\/a>\u3002<\/p>\n
\u6700\u540e\u8bf4\u4e00\u4e2a\u8ba9\u6211 wa \u6210\u50bb\u903c\u7684\u5730\u65b9\uff0c\u5c31\u662f\u6700\u540e\u7684\u8d44\u6e90\u56de\u6536\u3002\u3002\u3002\u56e0\u4e3a\u8fd9\u79cd\u865a\u6811\u7684\u9898\u901a\u5e38\u6211\u4eec\u662f\u4e0d\u80fd\u65e0\u8111 memset \u7684\uff0c\u4f46\u662f\u6211\u4eec\u521a\u624d\u6784\u5efa\u865a\u6811\u7684\u65f6\u5019\uff0c\u4e2d\u95f4\u53c8\u52a0\u5165\u4e86\u4e00\u4e9b\u65b0\u7684\u8282\u70b9\uff0c\u6240\u4ee5\u76f4\u63a5 for \u5faa\u73af\u90a3\u4e2a\u6570\u7ec4\u7684\u8bdd\u4f1a\u9519\u3002\u3002
\n\u6240\u4ee5\uff0c\u6700\u597d\u5728\u904d\u5386\u6811\u7ed3\u675f\u7684\u540c\u65f6\u628a\u8fd9\u4e9b\u4e0d\u7528\u7684\u4fe1\u606f\u90fd\u6e05\u7406\u6389\u3002\u3002\u3002<\/p>\n
http:\/\/uoj.ac\/submission\/387655<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
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