{"id":253,"date":"2012-06-15T16:36:28","date_gmt":"2012-06-15T08:36:28","guid":{"rendered":"http:\/\/www.shuizilong.com\/house\/?p=253"},"modified":"2012-06-18T18:06:42","modified_gmt":"2012-06-18T10:06:42","slug":"codeforces-round-124","status":"publish","type":"post","link":"https:\/\/www.shuizilong.com\/house\/archives\/codeforces-round-124\/","title":{"rendered":"Codeforces Round #124"},"content":{"rendered":"<h3>Brief description: <\/h3>\n<p>Problem A. Lexicographically Maximum Subsequence<br \/>\n\u7ed9\u5b9a\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u6c42\u91cd\u65b0\u6392\u5217\u8fd9\u4e2a\u5b57\u7b26\u4e32\u4e4b\u540e\u6240\u80fd\u5f97\u5230\u7684\u5b57\u5178\u5e8f\u6700\u5927\u7684\u4e32\u3002\uff08\u7565\u3002<\/p>\n<p>Problem B. Infinite Maze<br \/>\n\u7ed9\u5b9a\u4e00\u4e2a\u53ef\u5e73\u94fa\u7684\u8ff7\u5bab\uff0c\u95ee\u51fa\u53d1\u70b9\u6240\u5728\u7684\u533a\u57df\u662f\u5426\u662f\u5c01\u95ed\u7684\u3002\uff08\u8bb0\u5f55\u56db\u7ef4\u72b6\u6001 BFS() \u5373\u53ef\u3002\u3002\u3002\u5361\u6b65\u6570 TLE \u4e86\u4e24\u6b21\u3002\u3002<\/p>\n<p>Problem C. Paint Tree<br \/>\n\u7ed9\u5b9a\u4e00\u9897\u6811\uff0c\u548c\u5e73\u9762\u5185\u4e00\u7ec4\u70b9\u96c6\uff0c\u95ee\u662f\u5426\u5b58\u5728\u4e00\u4e2a\u5bf9\u5e94\u5173\u7cfb\u4f7f\u5f97\uff0c\u751f\u6210\u7684\u5e73\u9762\u56fe\u4e0d\u4ea7\u751f\u4ea4\u53c9\u3002<\/p>\n<p>Problem D. The Next Good String<br \/>\n\u3002Good String \u5b9a\u4e49\u4e3a\uff0c\u4e0d\u5b58\u5728\u957f\u5ea6\u5927\u4e8e\u7b49\u4e8e d \u7684\u56de\u6587\u5b50\u4e32\u3002\u7ed9\u5b9a\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u6c42\u8be5\u5b50\u4e32\u7684\u4e0b\u4e00\u4e2a Good String \u3002<\/p>\n<p>Problem E. Opening Portals<br \/>\n\u7ed9\u5b9a\u4e00\u4e2a n \u4e2a\u7ed3\u70b9\uff0cm \u6761\u8fb9\u65e0\u5411\u5e26\u6743\u56fe\uff0c\u9009\u4e2d\u5176\u4e2d k \u4e2a\u7ed3\u70b9\u4f5c\u4e3a\u4f20\u9001\u95e8\uff0c<br \/>\n\u5f53\u4e00\u4e2a\u4f20\u9001\u95e8\u88ab\u70b9\u4eae\u540e\uff0c\u53ef\u4ee5\u5728\u5176\u4ed6\u5df2\u88ab\u70b9\u4eae\u7684\u4f20\u9001\u95e8\u4e4b\u95f4\u505a\u65e0\u635f\u4f20\u9001\u3002<br \/>\n\u95ee\u4ece 1 \u53f7\u7ed3\u70b9\u51fa\u53d1\uff0c\u70b9\u4eae\u6240\u6709\u4f20\u9001\u95e8\u7684\u6700\u5c11\u4ee3\u4ef7\u3002<br \/>\n( .. 1 \u2264 k \u2264 n \u2264 10^5, m \u2264 10^5 .. .)<br \/>\n<!--more--><\/p>\n<p><!--more--><\/p>\n<h3>Analysis: <\/h3>\n<p>Problem C. Paint Tree<br \/>\n\u3002\u3002\u603b\u662f\u6709\u89e3\u3002\u6df1\u641c\u4e00\u6b21\u5f97\u5230 sz \u6570\u7ec4\u3002\u4e4b\u540e\u6839\u636e\u6781\u89d2\u5e8f\u9012\u5f52\u6784\u9020\u5373\u53ef\u3002<br \/>\n\u3002\u3002\u60f3\u660e\u767d\u5176\u5b9e\u8fd8\u662f\u7b80\u5355\u7684\u4e00\u9898\u3002<br \/>\n&#8230;<\/p>\n<p>Problem D. The Next Good String<br \/>\n\u3002\u6bd4\u8d5b\u7684\u65f6\u5019\u5199\u4e86\u4e2a\u6df1\u641c TLE \u4e86\u3002\u3002\u3002\u8d5b\u540e Sevenkplus \u544a\u8bc9\u6211\u5c31\u662f\u666e\u901a\u7684\u641c\u7d22\u3002\u3002\u3002<br \/>\n\u4e8e\u662f\u8dd1\u53bb\u770b\u4e86\u4e00\u4e0b 7k+ \u7684\u4ee3\u7801\u3002\u3002<\/p>\n<p>\u4e8e\u662f\u53d1\u73b0\u8fd9\u91cc\u6211\u7684\u4e3b\u8981\u9519\u8bef\u662f\u6ca1\u6709\u6ce8\u610f\u5230\u56de\u6587\u5b50\u4e32\u7684\u9012\u5f52\u6027\u8d28\u3002(\u5982\u679c\u5b58\u5728\u4e00\u4e2a\u957f\u5ea6\u4e3a x \u7684\u56de\u6587\u5b50\u4e32\uff0c\u5219\u5fc5\u7136\u5b58\u5728\u4e00\u4e2a\u957f\u5ea6 x-2 \u7684\u56de\u6587\u5b50\u4e32\u3002\u3002\u3002<\/p>\n<p>\u4e8e\u662f\u5229\u7528\u8fd9\u4e2a\u6027\u8d28 bool illegal() \u51fd\u6570\u53ea\u9700\u8981\u5224\u65ad d \u548c d+1 \u4e24\u4e2a\u957f\u5ea6\u5373\u53ef\u3002\u3002<\/p>\n<pre class=\"brush: cpp; collapse: false; light: false; title: ; toolbar: true; notranslate\" title=\"\">\r\nbool illegal(int x){\r\n    ++x; FOR_1(l, d, d+1){\r\n        if (l &gt; x) continue;\r\n        int h1 = A&#x5B;x] - A&#x5B;x-l]*P&#x5B;l], h2 = B&#x5B;x] - B&#x5B;x-l];\r\n        if (h1*P&#x5B;x-l] == h2) return true;\r\n    }\r\n    return false;\r\n}\r\n<\/pre>\n<p>\u6ce8\u610f\u5230\u8fd9\u91cc\u7684\u5b57\u7b26\u4e32 hash \u9700\u8981\u4e00\u4e9b\u6280\u5de7\uff0c\u4ee5\u907f\u514d\u590d\u6742\u7684\u4fee\u6539\u64cd\u4f5c<br \/>\n\uff08\u5b98\u65b9\u7684\u9898\u89e3\u91cc\u9762\u8fd9\u4e00\u6b65\u4f7f\u7528\u4e86\u6811\u72b6\u6570\u7ec4\u6765\u7ef4\u62a4 Hash\u3002\u3002\u3002<\/p>\n<p>\uff08\u8c8c\u4f3c\u6211\u7684\u7b97\u6cd5\u6846\u67b6\u548c\u5b98\u65b9\u9898\u89e3\u4e00\u6837\u3002\u3002\u5206\u4e3a\u4e24\u90e8\u3002<br \/>\n\u3002\u3002\u5148\u627e\u5230\u7b2c\u4e00\u4e2a\u8981\u4fee\u6539\u7684\u4f4d\u7f6e\u3002\u3002\u968f\u540e\u518d dfs()\u3002\u3002<br \/>\n\u5b9e\u9645\u4e5f\u53ef\u4ee5\u76f4\u63a5 dfs() \u3002\u3002\uff08\u53c2\u89c1 Sevenkplus \u7684\u4ee3\u7801\u3002\u3002\u3002<\/p>\n<p>Problem E. Opening Portals<br \/>\n\u9996\u5148\u6839\u636e\u4f20\u9001\u95e8\u7684\u6027\u8d28\uff0c\u5982\u679c\u6240\u6709\u70b9\u90fd\u662f\u4f20\u9001\u95e8\u7684\u8bdd\u90a3\u4e48\u7ed3\u679c\u5c31\u662f\u8be5\u56fe\u7684\u6700\u5c0f\u751f\u6210\u6811\u3002<br \/>\n\u5bf9\u4e8e\u53ea\u6709\u5176\u4e2d k \u4e2a\u7ed3\u70b9\u662f\u4f20\u9001\u95e8\u7684\u56fe\uff0c\u53ea\u8981\u5728\u539f\u7b97\u6cd5\u7684\u57fa\u7840\u4e0a\u7a0d\u4f5c\u4fee\u6539\u5373\u53ef\u3002<br \/>\n\u5177\u4f53\uff0c\u5bf9\u6bcf\u4e2a\u70b9\u6c42\u51fa P[i] \u548c D[i] \u3002\uff08\u8868\u793a\u8ddd\u79bb\u8fd9\u4e2a\u70b9\u6700\u8fd1\u7684\u4f20\u9001\u95e8\u548c\u5176\u8ddd\u79bb\u3002\u3002\u3002<br \/>\n\u4e4b\u540e\u5bf9\u6bcf\u6761\u8fb9\uff0c\u518d\u6839\u636e D[x] + D[y] + w \u4f5c\u4e3a\u5173\u952e\u5b57\u8dd1\u6700\u5c0f\u751f\u6210\u6811\u3002\u3002<\/p>\n<p>\u4ee5\u4e0a\u5206\u522b\u7528\u4e00\u6b21\u591a\u6e90 Dijkstra()\uff0c\u548c\u7a0d\u4f5c\u4fee\u6539\u7684 Kruskal() \u5373\u53ef\u3002<br \/>\n\uff08\u56e0\u6b64\u611f\u89c9\u7f16\u7801\u96be\u5ea6\u4e0a\u4e5f\u8981\u5f31\u4e8e D \u9898\u3002\u3002\u3002<\/p>\n<h3>Code: <\/h3>\n<p><a href=\"http:\/\/codeforces.com\/contest\/196\/submission\/1787876\">A<\/a> <a href=\"http:\/\/codeforces.com\/contest\/196\/submission\/1792578\">B<\/a> <a href=\"http:\/\/codeforces.com\/contest\/196\/submission\/1804196\">C<\/a> <a href=\"http:\/\/codeforces.com\/contest\/196\/submission\/1804052\">D<\/a> <a href=\"http:\/\/codeforces.com\/contest\/196\/submission\/1808512\">E<\/a><\/p>\n<h3>External link: <\/h3>\n<p><a href=\"http:\/\/codeforces.com\/contest\/196\/room\/4\">http:\/\/codeforces.com\/contest\/196\/room\/4<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Brief description: Problem A. Lexicographically Maximum Subsequence \u7ed9\u5b9a\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u6c42\u91cd\u65b0\u6392\u5217\u8fd9\u4e2a\u5b57\u7b26\u4e32\u4e4b\u540e\u6240\u80fd\u5f97\u5230\u7684\u5b57\u5178\u5e8f\u6700\u5927\u7684\u4e32\u3002\uff08\u7565\u3002 Problem B. Infinite Maze \u7ed9\u5b9a\u4e00\u4e2a\u53ef\u5e73\u94fa\u7684\u8ff7\u5bab\uff0c\u95ee\u51fa\u53d1\u70b9\u6240\u5728\u7684\u533a\u57df\u662f\u5426\u662f\u5c01\u95ed\u7684\u3002\uff08\u8bb0\u5f55\u56db\u7ef4\u72b6\u6001 BFS() \u5373\u53ef\u3002\u3002\u3002\u5361\u6b65\u6570 TLE \u4e86\u4e24\u6b21\u3002\u3002 Problem C. Paint Tree \u7ed9\u5b9a\u4e00\u9897\u6811\uff0c\u548c\u5e73\u9762\u5185\u4e00\u7ec4\u70b9\u96c6\uff0c\u95ee\u662f\u5426\u5b58\u5728\u4e00\u4e2a\u5bf9\u5e94\u5173\u7cfb\u4f7f\u5f97\uff0c\u751f\u6210\u7684\u5e73\u9762\u56fe\u4e0d\u4ea7\u751f\u4ea4\u53c9\u3002 Problem D. The Next Good String \u3002Good String \u5b9a\u4e49\u4e3a\uff0c\u4e0d\u5b58\u5728\u957f\u5ea6\u5927\u4e8e\u7b49\u4e8e d \u7684\u56de\u6587\u5b50\u4e32\u3002\u7ed9\u5b9a\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u6c42\u8be5\u5b50\u4e32\u7684\u4e0b\u4e00\u4e2a Good String \u3002 Problem E. Opening Portals \u7ed9\u5b9a\u4e00\u4e2a n \u4e2a\u7ed3\u70b9\uff0cm \u6761\u8fb9\u65e0\u5411\u5e26\u6743\u56fe\uff0c\u9009\u4e2d\u5176\u4e2d k \u4e2a\u7ed3\u70b9\u4f5c\u4e3a\u4f20\u9001\u95e8\uff0c \u5f53\u4e00\u4e2a\u4f20\u9001\u95e8\u88ab\u70b9\u4eae\u540e\uff0c\u53ef\u4ee5\u5728\u5176\u4ed6\u5df2\u88ab\u70b9\u4eae\u7684\u4f20\u9001\u95e8\u4e4b\u95f4\u505a\u65e0\u635f\u4f20\u9001\u3002 \u95ee\u4ece 1 \u53f7\u7ed3\u70b9\u51fa\u53d1\uff0c\u70b9\u4eae\u6240\u6709\u4f20\u9001\u95e8\u7684\u6700\u5c11\u4ee3\u4ef7\u3002 ( .. 1 \u2264 k [&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":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[18],"tags":[],"class_list":["post-253","post","type-post","status-publish","format-standard","hentry","category-codeforces"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p2tdP7-45","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/posts\/253","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=253"}],"version-history":[{"count":1,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/posts\/253\/revisions"}],"predecessor-version":[{"id":254,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/posts\/253\/revisions\/254"}],"wp:attachment":[{"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/media?parent=253"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/categories?post=253"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.shuizilong.com\/house\/wp-json\/wp\/v2\/tags?post=253"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}