{"id":2981,"date":"2023-06-05T23:18:16","date_gmt":"2023-06-05T15:18:16","guid":{"rendered":"https:\/\/www.shuizilong.com\/house\/?p=2981"},"modified":"2023-06-05T23:18:16","modified_gmt":"2023-06-05T15:18:16","slug":"luogu-p3629-apio2010-%e5%b7%a1%e9%80%bb","status":"publish","type":"post","link":"https:\/\/www.shuizilong.com\/house\/archives\/luogu-p3629-apio2010-%e5%b7%a1%e9%80%bb\/","title":{"rendered":"Luogu P3629. [APIO2010] \u5de1\u903b"},"content":{"rendered":"<ul>\n<li><a href=\"https:\/\/www.luogu.com.cn\/problem\/P3629\">https:\/\/www.luogu.com.cn\/problem\/P3629<\/a><\/li>\n<\/ul>\n<p>\u6c42\u4e24\u6b21\u76f4\u5f84\u7684\u9ad8\u7ea7\u505a\u6cd5\u597d\u50cf\u5df2\u7ecf\u70c2\u5927\u8857\u4e86\u3002\u3002<br \/>\n\u8fd9\u91cc\u8d34\u4e00\u4e0b\u66f4\u5e38\u89c4\u7684\u6362\u6839 dp\u3002\u3002<\/p>\n<p>\u505a\u6cd5\u5c31\u662f <a href=\"https:\/\/www.shuizilong.com\/house\/archives\/spoj-twopaths-two-paths\/\">Two Paths<\/a> \u591a\u8003\u8651\u4e00\u79cd\u60c5\u51b5\u5373\u53ef~~<\/p>\n<pre class=\"brush: cpp; light: false; title: ; toolbar: true; notranslate\" title=\"\">\r\n#include &lt;lastweapon\/io&gt;\r\nusing namespace lastweapon;\r\n\r\nconst int N = int(3e5) + 9;\r\n\r\nint dn&#x5B;N], up&#x5B;N]; \/\/ \u5b50\u6811\u5185\u76f4\u5f84\uff0c\u5b50\u6811\u5916\u76f4\u5f84\r\nint d&#x5B;N]&#x5B;4], e&#x5B;N]; \/\/ \u5b50\u6570\u5185 top4 \u6700\u957f\u8ddd\u79bb\uff0c\u5b50\u6811\u5916\u6700\u957f\u8ddd\u79bb\r\nVI adj&#x5B;N]; int n, K, z;\r\n\r\nvoid upd(int d&#x5B;], int v) {\r\n    if (v &gt; d&#x5B;0]) d&#x5B;3] = d&#x5B;2], d&#x5B;2] = d&#x5B;1], d&#x5B;1] = d&#x5B;0], d&#x5B;0] = v;\r\n    else if (v &gt; d&#x5B;1]) d&#x5B;3] = d&#x5B;2], d&#x5B;2] = d&#x5B;1], d&#x5B;1] = v;\r\n    else if (v &gt; d&#x5B;2]) d&#x5B;3] = d&#x5B;2], d&#x5B;2] = v;\r\n    else if (v &gt; d&#x5B;3]) d&#x5B;3] = v;\r\n}\r\n\r\nvoid dfs1(int u = 1, int p = 0) {\r\n    for (auto v: adj&#x5B;u]) if (v != p) {\r\n        dfs1(v, u);\r\n        upd(d&#x5B;u], d&#x5B;v]&#x5B;0] + 1);\r\n        checkMax(dn&#x5B;u], dn&#x5B;v]);\r\n    }\r\n    checkMax(dn&#x5B;u], d&#x5B;u]&#x5B;0] + d&#x5B;u]&#x5B;1]);\r\n}\r\n\r\nvoid dfs2(int u = 1, int p = 0) {\r\n    for (auto v: adj&#x5B;u]) if (v != p) {\r\n        checkMax(up&#x5B;v], up&#x5B;u]);\r\n        checkMax(e&#x5B;v], e&#x5B;u] + 1);\r\n        int t = d&#x5B;v]&#x5B;0] + 1;\r\n        if (d&#x5B;u]&#x5B;0] == t) {\r\n            checkMax(up&#x5B;v], d&#x5B;u]&#x5B;1] + d&#x5B;u]&#x5B;2]);\r\n            checkMax(up&#x5B;v], d&#x5B;u]&#x5B;1] + e&#x5B;u]);\r\n            checkMax(e&#x5B;v], d&#x5B;u]&#x5B;1] + 1);\r\n        }\r\n        else {\r\n            if (d&#x5B;u]&#x5B;1] == t) checkMax(up&#x5B;v], d&#x5B;u]&#x5B;0] + d&#x5B;u]&#x5B;2]);\r\n            else checkMax(up&#x5B;v], d&#x5B;u]&#x5B;0] + d&#x5B;u]&#x5B;1]);\r\n            checkMax(up&#x5B;v], d&#x5B;u]&#x5B;0] + e&#x5B;u]);\r\n            checkMax(e&#x5B;v], d&#x5B;u]&#x5B;0] + 1);\r\n        }\r\n        dfs2(v, u);\r\n    }\r\n\r\n    if (K == 2) checkMax(z, dn&#x5B;u] + up&#x5B;u]);\r\n    upd(d&#x5B;u], e&#x5B;u]); checkMax(z, d&#x5B;u]&#x5B;0] + d&#x5B;u]&#x5B;1] + (K == 2 ? d&#x5B;u]&#x5B;2] + d&#x5B;u]&#x5B;3] : 0));\r\n}\r\n\r\nint main() {\r\n\r\n#ifndef ONLINE_JUDGE\r\n    freopen(&quot;in.txt&quot;, &quot;r&quot;, stdin);\r\n    \/\/freopen(&quot;\/Users\/minakokojima\/Documents\/GitHub\/ACM-Training\/Workspace\/out.txt&quot;, &quot;w&quot;, stdout);\r\n#endif\r\n\r\n    RD(n, K); DO(n-1) {\r\n        int x, y; RD(x, y);\r\n        adj&#x5B;x].PB(y);\r\n        adj&#x5B;y].PB(x);\r\n    }\r\n\r\n    dfs1(); dfs2();\r\n    cout &lt;&lt; 2*(n-1) - z + K &lt;&lt; endl;\r\n}\r\n\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>https:\/\/www.luogu.com.cn\/problem\/P3629 \u6c42\u4e24\u6b21\u76f4\u5f84\u7684\u9ad8\u7ea7\u505a\u6cd5\u597d\u50cf\u5df2\u7ecf\u70c2\u5927\u8857\u4e86\u3002\u3002 \u8fd9\u91cc\u8d34\u4e00\u4e0b\u66f4\u5e38\u89c4\u7684\u6362\u6839 dp\u3002\u3002 \u505a\u6cd5\u5c31\u662f Two Paths \u591a\u8003\u8651\u4e00\u79cd\u60c5\u51b5\u5373\u53ef~~ #include &lt;lastweapon\/io&gt; using namespace lastweapon; const int N = int(3e5) + 9; int dn&#x5B;N], up&#x5B;N]; \/\/ \u5b50\u6811\u5185\u76f4\u5f84\uff0c\u5b50\u6811\u5916\u76f4\u5f84 int d&#x5B;N]&#x5B;4], e&#x5B;N]; \/\/ \u5b50\u6570\u5185 top4 \u6700\u957f\u8ddd\u79bb\uff0c\u5b50\u6811\u5916\u6700\u957f\u8ddd\u79bb VI adj&#x5B;N]; int n, K, z; void upd(int d&#x5B;], int v) { if (v &gt; d&#x5B;0]) d&#x5B;3] = d&#x5B;2], d&#x5B;2] = d&#x5B;1], d&#x5B;1] [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[1],"tags":[],"class_list":["post-2981","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p2tdP7-M5","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/posts\/2981","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/comments?post=2981"}],"version-history":[{"count":1,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/posts\/2981\/revisions"}],"predecessor-version":[{"id":2982,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/posts\/2981\/revisions\/2982"}],"wp:attachment":[{"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/media?parent=2981"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/categories?post=2981"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/tags?post=2981"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}