{"id":401,"date":"2018-11-10T21:54:54","date_gmt":"2018-11-10T13:54:54","guid":{"rendered":"http:\/\/SmokeyDays.top\/wordpress\/?p=401"},"modified":"2018-11-10T21:55:35","modified_gmt":"2018-11-10T13:55:35","slug":"noip2018-%e8%b5%9b%e9%81%93%e4%bf%ae%e5%bb%ba","status":"publish","type":"post","link":"http:\/\/SmokeyDays.top\/wordpress\/2018\/11\/10\/noip2018-%e8%b5%9b%e9%81%93%e4%bf%ae%e5%bb%ba\/","title":{"rendered":"NOIP2018 \u8d5b\u9053\u4fee\u5efa"},"content":{"rendered":"

\u4e00\u9053\u6811\u5f62DP\u88f8\u9898\u3002
\n\u56e0\u4e3a\u90e8\u5206\u5206\u7ed9\u5f97\u5f88\u8db3\uff0c\u6240\u4ee5\u6211\u5728\u8003\u573a\u4e0a\u5148\u6253\u4e86\u4e00\u5806\u90e8\u5206\u5206\uff0c\u5efa\u4e865\u4e2a\u547d\u540d\u7a7a\u95f4\u3002
\n\u7136\u540e\u5728\u6253\u4e8c\u53c9\u6811\u7684\u90e8\u5206\u5206\u7684\u65f6\u5019\u60f3\u5230\u4e86\u6b63\u89e3\u3002\uff08\u867d\u7136\u53ef\u80fd\u4e8c\u5206\u5199\u6302\u4e86\uff09
\n\u9898\u76ee\u5927\u610f\uff1a\u7ed9\u5b9a\u4e00\u68f5\u5e26\u6743\u6811\uff0c\u5c06\u5b83\u7684\u4e00\u90e8\u5206\u62c6\u6210\\(m\\)\u6761\u94fe\uff0c\u4f7f\u5f97\u6743\u503c\u6700\u77ed\u7684\u94fe\u7684\u6743\u503c\u6700\u5927\u3002
\n\u6700\u5c0f\u7684\u6c42\u6700\u5927\uff0c\u5f53\u7136\u6ee1\u8db3\u65e0\u540e\u6548\u6027\uff0c\u6240\u4ee5\u6211\u4eec\u8003\u8651\u4e8c\u5206\u7b54\u6848\u3002
\n\u7136\u540e\u6211\u4eec\u8003\u8651\u68c0\u9a8c\u3002\u9996\u5148\uff0c\u5f88\u5bb9\u6613\u53ef\u4ee5\u53d1\u73b0\u7b54\u6848\u5177\u6709\u65e0\u540e\u6548\u6027\u3002\u6362\u53e5\u8bdd\u8bf4\uff0c\u6bcf\u4e2a\u5b50\u6811\u5728\u8ba1\u7b97\u51fa\u5b83\u5bf9\u7b54\u6848\u7684\u8d21\u732e\u4e4b\u540e\uff0c\u5c31\u53ea\u9700\u8981\u8ba1\u7b97\u51fa\u5b83\u5bf9\u7236\u8282\u70b9\u7684\u8d21\u732e\u3002
\n\u8fd9\u662f\u56e0\u4e3a\uff0c\u6bcf\u4e00\u4e2a\u7236\u8282\u70b9\uff0c\u5b83\u80fd\u4f7f\u7528\u7684\u4ec5\u6709\u5b50\u6811\u7684\u4e00\u6761\u94fe\uff0c\u800c\u4e0d\u662f\u6574\u4e2a\u5b50\u6811\u7684\u4fe1\u606f\u3002
\n\u6545\u800c\uff0c\u6211\u4eec\u53ea\u9700\u8981\u300c\u53ef\u4ee5\u63d0\u4f9b\u7ed9\u7236\u8282\u70b9\u7684\u90a3\u6761\u94fe\u300d\u7684\u503c\u66f4\u65b0\u4e0a\u53bb\u5373\u53ef\u3002\u6211\u4eec\u7528\\(f_{x}\\)\u8868\u8fbe\u8fd9\u4e2a\u4e0a\u4f20\u7684\u503c\u3002
\n\u5e76\u4e14\uff0c\u5bf9\u4e8e\u6bcf\u68f5\u5b50\u6811\u662f\u53ef\u4ee5\u8d2a\u5fc3\u5730\u5904\u7406\u7684\u2014\u2014\u5982\u679c\u4e00\u68f5\u5b50\u6811\u4e2d\u7684\u4e00\u6761\u94fe\u53ef\u4ee5\u548c\u53e6\u4e00\u6761\u94fe\u7ec4\u6210\u4e00\u6761\u5408\u6cd5\u7684\u94fe\uff0c\u90a3\u5c31\u6ca1\u5fc5\u8981\u628a\u5b83\u4e0a\u4f20\u4e86\u3002
\n\u8fd9\u662f\u56e0\u4e3a\uff0c\u5982\u679c\u4e0d\u4e0a\u4f20\uff0c\u4e00\u5b9a\u53ef\u4ee5\u5bf9\u7b54\u6848\u4ea7\u751f1\u7684\u8d21\u732e\uff1b\u5982\u679c\u4e0a\u4f20\u4e86\uff0c\u4ec5\u4ec5\u662f\u6709\u53ef\u80fd\u5bf9\u7b54\u6848\u4ea7\u751f1\u7684\u8d21\u732e\u3002
\n\u90a3\u4e48\u6211\u4eec\u5bf9\u6bcf\u4e2a\u5b50\u6811\u5206\u522b\u8003\u8651\u3002\u8fd9\u5c31\u8f6c\u5316\u4e3a\u4e86\u4e00\u4e2a\u65b0\u7684\u95ee\u9898\uff1a
\n\u300c\u5bf9\u4e8e\u4e00\u4e2a\u957f\u5ea6\u4e3a\\(n\\)\u7684\u5e8f\u5217\uff0c\u53d6\u51fa\u5176\u4e2d\u5c3d\u53ef\u80fd\u591a\u7684\u6570\u5bf9\u6216\u6570\uff0c\u4f7f\u5f97\u6570\u5bf9\u7684\u548c\u6216\u6570\u7684\u503c\u5927\u4e8e\u7ed9\u5b9a\u503c\uff0c\u5e76\u4e14\u5728\u6709\u9057\u7559\u6570\u7684\u60c5\u51b5\u4e0b\u4f7f\u5f97\u9057\u7559\u7684\u6570\u7684\u503c\u6700\u5927\u3002\u300d
\n\u8fd9\u4e2a\u95ee\u9898\u8981\u600e\u4e48\u505a\u5462\uff1f\u5c06\u5b83\u4eec\u4ece\u5c0f\u5230\u5927\u6392\u5e8f\uff0c\u90a3\u4e48\u5bf9\u4e8e\u5927\u4e8e\u7ed9\u5b9a\u503c\u7684\u6570\uff0c\u5355\u72ec\u9009\u53d6\u662f\u66f4\u4f18\u7684\u3002
\n\u7136\u540e\u5904\u7406\u5269\u4e0b\u6765\u7684\u6570\u3002\u7528\u53cc\u6307\u9488\u505a\u3002
\n\u5982\u679c\u53f3\u6307\u9488\u7684\u6570\u53ef\u4ee5\u4e0e\u5de6\u6307\u9488\u6307\u7684\u6570\u7ec4\u6210\u5408\u6cd5\u6570\u5bf9\u5c31\u628a\u53f3\u6307\u9488\u63a8\u5165\u6808\u4e2d\uff0c\u76f4\u5230\u6ca1\u6709\u5408\u6cd5\u7684\u53f3\u6307\u9488\uff0c\u5c31\u8003\u8651\u6808\u4e2d\u662f\u5426\u4e3a\u7a7a\u3002
\n\u5982\u679c\u4e0d\u4e3a\u7a7a\u5c31\u8bf4\u660e\u5b58\u5728\u4e00\u4e2a\u53ef\u4ee5\u548c\u5de6\u6307\u9488\u5339\u914d\u7684\u6570\uff0c\u90a3\u4e48\u5c31\u5c06\u7b54\u6848\u52a0\u4e00\uff0c\u5426\u5219\u5de6\u6307\u9488\u5c31\u627e\u4e0d\u5230\u6570\u548c\u5b83\u5339\u914d\u4e86\uff0c\u90a3\u4e48\u5c31\u7528\u5b83\u6765\u66f4\u65b0\\(f{x}\\)\u5de6\u6307\u9488\u5f80\u53f3\u63a8\u3002\u4e00\u76f4\u5230\u5e8f\u5217\u4e3a\u7a7a\u3002
\n\u7136\u540e\uff0c\u5bf9\u4e8e\u5269\u4e0b\u7684\u6570\uff0c\u5b83\u4eec\u4e00\u5b9a\u90fd\u53ef\u4ee5\u7ec4\u6210\u5408\u6cd5\u6570\u5bf9\u2014\u2014\u8fd9\u662f\u56e0\u4e3a\u6240\u6709\u88ab\u63a8\u5165\u6808\u4e2d\u7684\u6570\uff0c\u90fd\u53ef\u4ee5\u548c\u4e00\u4e2a\u6bd4\u6808\u4e2d\u6700\u5c0f\u6570\u8fd8\u8981\u5c0f\u7684\u6570\u7ec4\u6210\u5408\u6cd5\u6570\u5bf9\u3002
\n\u90a3\u4e48\uff0c\u6211\u4eec\u8003\u8651\u5269\u4e0b\u7684\u6570\u7684\u6570\u91cf\u7684\u5947\u5076\u6027\u3002\u5982\u679c\u662f\u5947\u6570\u4e2a\uff0c\u90a3\u4e48\u5c31\u8ba1\u7b97\u7b54\u6848\u4e4b\u540e\u7528\u6700\u5927\u503c\u6765\u66f4\u65b0\\(f_{x}\\)\u3002
\n\u8fd9\u5c31\u505a\u5b8c\u4e86\u3002<\/p>\n

#include<iostream>\r\n#include<cstdio>\r\n#include<algorithm>\r\n#include<cstring>\r\nstruct ee{\r\n\tint v;\r\n\tint w;\r\n\tint nxt;\r\n}e[50005];\r\nint h[50005],et=0;\r\nint n,m;\r\ninline void add(int u,int v,int w){\r\n\te[++et]=(ee){v,w,h[u]};\r\n\th[u]=et;\r\n}\r\nint MN,rt=0,f[50005],nw;\r\nint st[50005],tp=0,st2[50005],tp2=0;\r\ninline void dfs(int X){\r\n\tfor(int i=h[X];i;i=e[i].nxt){\r\n\t\tdfs(e[i].v);\r\n\t}\r\n\ttp=0,tp2=0;\r\n\tfor(int i=h[X];i;i=e[i].nxt){\r\n\t\tst[++tp]=f[e[i].v]+e[i].w;\r\n\t}\r\n\tstd::sort(st+1,st+1+tp);\r\n\twhile(tp&&st[tp]>=MN){\r\n\t\t--tp;\r\n\t\t++rt;\r\n\t}\r\n\tfor(int i=1;i<=tp;++i){\r\n\t\twhile(i<tp&&st[i]+st[tp]>=MN){\r\n\t\t\tst2[++tp2]=st[tp];\r\n\t\t\t--tp;\r\n\t\t}\r\n\t\tif(tp2){\r\n\t\t\t--tp2;\r\n\t\t\t++rt;\r\n\t\t}else{\r\n\t\t\tf[X]=st[i];\r\n\t\t}\r\n\t} \r\n\tif(tp2&1){\r\n\t\tf[X]=st2[1];\r\n\t}\r\n\trt+=(tp2>>1);\r\n} \r\ninline bool chck(int X){\r\n\tstd::memset(f,0,sizeof(f));\r\n\tMN=X;\r\n\trt=0;\r\n\tdfs(1);\r\n\tif(rt>=m){\r\n\t\treturn 1;\r\n\t}else{\r\n\t\treturn 0;\r\n\t}\r\n}\r\nvoid init(){\r\n\tscanf(\"%d%d\",&n,&m);\r\n\tint u,v,w;\r\n\tfor(int i=1;i<n;++i){\r\n\t\tscanf(\"%d%d%d\",&u,&v,&w);\r\n\t\tif(u>v){\r\n\t\t\tu^=v^=u^=v;\r\n\t\t}\r\n\t\tadd(u,v,w);\r\n\t}\r\n\tint l=0,r=0x3f3f3f3f,mid,ans=0;\r\n\twhile(l<=r){\r\n\t\tmid=(l+r)>>1;\r\n\t\tif(chck(mid)){\r\n\t\t\tl=mid+1;\r\n\t\t\tans=mid;\r\n\t\t}else{\r\n\t\t\tr=mid-1;\r\n\t\t}\r\n\t}\r\n\tprintf(\"%d\\n\",ans);\r\n}\r\nint main(){\r\n\tinit();\r\n\treturn 0;\r\n}<\/code><\/pre>\n
 <\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e00\u9053\u6811\u5f62DP\u88f8\u9898\u3002 \u56e0\u4e3a\u90e8\u5206\u5206\u7ed9\u5f97\u5f88\u8db3\uff0c\u6240\u4ee5\u6211\u5728\u8003\u573a\u4e0a\u5148\u6253\u4e86\u4e00\u5806\u90e8\u5206\u5206\uff0c\u5efa\u4e865\u4e2a\u547d\u540d\u7a7a\u95f4\u3002 \u7136\u540e\u5728\u6253\u4e8c\u53c9\u6811\u7684\u90e8 … <\/p>\n
\u7ee7\u7eed\u9605\u8bfb\u201cNOIP2018 \u8d5b\u9053\u4fee\u5efa\u201d<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[10,30,51,6,5],"tags":[],"_links":{"self":[{"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/posts\/401"}],"collection":[{"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/comments?post=401"}],"version-history":[{"count":1,"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/posts\/401\/revisions"}],"predecessor-version":[{"id":402,"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/posts\/401\/revisions\/402"}],"wp:attachment":[{"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/media?parent=401"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/categories?post=401"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/SmokeyDays.top\/wordpress\/wp-json\/wp\/v2\/tags?post=401"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}