{"id":314,"date":"2013-01-22T09:41:00","date_gmt":"2013-01-22T01:41:00","guid":{"rendered":"http:\/\/nike0good.jp1.rpvhost.net\/219"},"modified":"2013-01-22T09:41:00","modified_gmt":"2013-01-22T01:41:00","slug":"poj_1228_stable_convex_hull","status":"publish","type":"post","link":"https:\/\/nike0good.com\/?p=314","title":{"rendered":"POJ 1228(\u7a33\u5b9a\u51f8\u5305)"},"content":{"rendered":"\n\n\n
\n
Language:\n\n\n\n
Time Limit:<\/strong> 1000MS<\/td>\n <\/td>\nMemory Limit:<\/strong> 10000K<\/td>\n<\/tr>\n
Total Submissions:<\/strong> 8990<\/td>\n <\/td>\nAccepted:<\/strong> 2383<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Description<\/p>\n

\nKamran the Believer\u7ee7\u627f\u4e86\u7956\u6bcd\u7684\u4e00\u4e2a\u51f8\u591a\u8fb9\u5f62\u5e84\u56ed. \u5e84\u56ed\u5916\u56f4\u7528\u7ef3\u5b50\u548c\u6728\u6869\u56f4\u8d77. \u4f46\u4e00\u4e9b\u7ef3\u5b50\u548c\u6728\u6869\u7f3a\u5931\u4e86.\u5e2e\u5fd9\u770b\u4e00\u4e0b\u7528\u5269\u4f59\u6728\u6869\u56f4\u8d77\u7684\u5e84\u56ed\u662f\u5426\u662f\u7a33\u5b9a\u51f8\u5305\uff08\u5373\u5269\u4e0b\u7684\u9489\u5b50\u80fd\u786e\u5b9a\u4e00\u4e2a\u552f\u4e00\u7684\u51f8\u5305\uff09.<\/div>\n

Input<\/p>\n

\n\u7b2c\u4e00\u884c\u4e00\u4e2a\u6570\u636e\u7ec4\u6570 t (1 <= t <= 10). <\/div>\n
\n\u5bf9\u4e8e\u6bcf\u7ec4\u6570\u636e\uff0c\u7b2c\u4e00\u884c\u4e3a n (1 <= n <= 1000) \u8868\u793a\u6728\u6869\u6570. \u63a5\u4e0b\u6765n\u884c\uff0c\u6bcf\u884c\u4e3a\u6728\u6869\u5750\u6807(x,y)\uff0c\u4fdd\u8bc1\u6574\u6570.<\/span><\/div>\n

Output<\/p>\n

\n \u5bf9\u6bcf\u7ec4\u6570\u636e\u8f93\u51faYES \u6216 NO \uff0c\u8868\u793a\u5176\u662f\u5426\u7a33\u5b9a.<\/div>\n

Sample Input<\/p>\n

1\n6\n0 0\n1 2\n3 4\n2 0\n2 4\n5 0\n<\/pre>\n
Sample Output<\/p>\n
NO<\/pre>\n
Source<\/p>\n
\nTehran 2002 Preliminary<\/a><\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u8981\u60f3\u8ba9\u4e00\u4e2a\u51f8\u5305\u7a33\u5b9a\uff0c\u5f53\u4e14\u4ec5\u5f53\u51f8\u5305\u4e0a\u4efb\u610f\u4e00\u6761\u8fb9\u67093\u4e2a\u4ee5\u4e0a\u7684\u6728\u6869\uff08\u5305\u62ec\u7aef\u70b9<\/span>\uff09<\/span><\/p>\n
\u8bc1\u660e\uff1a<\/span><\/p>\n
\"\"
\n<\/span><\/p>\n
\u53ea\u8981\u5728\u5efa\u5b8c\u51f8\u5305\u540e\uff0c\u679a\u4e3e\uff0c\u8fb9\u4e0a\u7684\u7b2c3\u70b9\u5373\u53ef\u3002<\/span><\/p>\n
<\/span><\/p>\n
#include<cstdio>\n#include<cstring>\n#include<cstdlib>\n#include<cmath>\n#include<cctype>\n#include<iostream>\n#include<functional>\n#include<algorithm>\nusing namespace std;\n#define MAXT (10+10)\n#define MAXN (1000+10)\n\/\/#define sqr( x ) (x*x)\nint sqr(int x){return x*x;}\nstruct P\n{\n\tint x,y;\n\tP(){}\n\tP(int _x,int _y):x(_x),y(_y){}\n\tfriend istream& operator>>(istream &cin,P &a)\n\t{\n\t\tcin>>a.x>>a.y;return cin;\n\t}\n\tfriend double dis(P a,P b)\n\t{\n\t\treturn sqrt(double(sqr(a.x-b.x)+sqr(a.y-b.y)));\n\t}\n}a[MAXN];\nstruct V\n{\n\tint x,y;\n\tV(){}\n\tV(int _x,int _y):x(_x),y(_y){}\n\tV(P a,P b):x(b.x-a.x),y(b.y-a.y){}\n\tfriend int operator*(V a,V b)\n\t{\n\t\treturn a.x*b.y-a.y*b.x;\n\t}\n};\nint cmp(P A,P B)\n{\n\tint temp=V(a[1],A)*V(a[1],B);\n\tif (temp>0) return 1;\n\telse if (temp==0&&dis(a[1],A)<dis(a[1],B)) return 1;\n\telse return 0;\n}\nint t,n,st[MAXN];\nbool solve()\n{\n\tint size=1;st[0]=1;\n\tst[1]=1;\n\tint j=2;\n\twhile (j<=n)\n\t{\n\t\tif (size<2||V(a[st[size-1]],a[st[size]])*V(a[st[size]],a[j])>0)\n\t\t{\n\t\t\tst[++size]=j++;\n\t\t}\n\t\telse size--;\n\t}\n\ta[++n]=a[1];\n\tst[++size]=n;\n\n\tfor (int i=1;i<size;i++)\n\t{\n\t\/*\n\t\tint k=st[i-1]+1;\n\t\tfor (;k<st[i+1];k++)\n\t\t\tif (k!=st[i]&&V(a[st[i]],a[st[i+1]])*V(a[st[i]],a[st[k]])==0) break;\n\t\tif (k==st[i+1]) return 0;\n\t*\/\n\t\tint k=1;\n\t\tfor (;k<n;k++)\n\t\t\tif (k!=st[i]&&k!=st[i+1]&&V(a[st[i]],a[st[i+1]])*V(a[st[i]],a[k])==0) break;\n\t\tif (k==n) return 0;\n\t}\n\treturn size>=4;\n}\nint main()\n{\n\/\/\tfreopen("poj1228.in","r",stdin);\n\tcin>>t;\n\twhile (t--)\n\t{\n\t\tcin>>n;\n\t\tfor (int i=1;i<=n;i++) cin>>a[i];\n\t\tif (n<6)\n\t\t{\n\t\t\tcout<<"NOn";\n\t\t\tcontinue;\n\t\t}\n\t\tint p=1;\n\t\tfor (int i=2;i<=n;i++) if (a[i].x<a[p].x||(a[i].x==a[p].x)&&(a[i].y<a[p].y)) p=i;\n\t\tswap(a[1],a[p]);\n\t\tsort(a+2,a+1+n,cmp);\n\/\/\t\tcout<<dis(P(0,0),P(1,0))<<dis(P(0,0),P(1,0));\n\t\tif (solve()) cout<<"YESn";\n\t\telse cout<<"NOn";\n\t}\n\treturn 0;\n}<\/pre>\n
\n\u5907\u6ce8\uff1a\u4e0d\u77e5\u4e3a\u4f55\uff0c\u5c06sqr\u66ff\u6362\u6210define \u7ed3\u679c\u4f1a\u8f93\u51fa"nan"\u2026\u2026\u5f69<\/span>\u86cb<\/span>\uff1f<\/span><\/span><\/p>\n

\n<\/span><\/p>\n

\n<\/span><\/p>\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
Language: Default Grandpa’s Estate Time Limit: 100 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_coblocks_attr":"","_coblocks_dimensions":"","_coblocks_responsive_height":"","_coblocks_accordion_ie_support":"","footnotes":""},"categories":[3],"tags":[57],"class_list":["post-314","post","type-post","status-publish","format-standard","hentry","category-defaultcategory","tag-convex_hull"],"yoast_head":"\nPOJ 1228(\u7a33\u5b9a\u51f8\u5305) - nike0good<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/nike0good.com\/?p=314\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"POJ 1228(\u7a33\u5b9a\u51f8\u5305) - nike0good\" \/>\n<meta property=\"og:description\" content=\"Language: Default Grandpa's Estate Time Limit: 100 […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/nike0good.com\/?p=314\" \/>\n<meta property=\"og:site_name\" content=\"nike0good\" \/>\n<meta property=\"article:published_time\" content=\"2013-01-22T01:41:00+00:00\" \/>\n<meta property=\"og:image\" content=\"http:\/\/nike0good.jp1.rpvhost.net\/wp-content\/uploads\/csdn\/other_site\/img_my_1358819035_4823.png\" \/>\n<meta name=\"author\" content=\"nike0good\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u4f5c\u8005\" \/>\n\t<meta name=\"twitter:data1\" content=\"nike0good\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 \u5206\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314\"},\"author\":{\"name\":\"nike0good\",\"@id\":\"https:\\\/\\\/nike0good.com\\\/#\\\/schema\\\/person\\\/4defa38da89de87e400861e73396baad\"},\"headline\":\"POJ 1228(\u7a33\u5b9a\u51f8\u5305)\",\"datePublished\":\"2013-01-22T01:41:00+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314\"},\"wordCount\":54,\"commentCount\":0,\"image\":{\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314#primaryimage\"},\"thumbnailUrl\":\"http:\\\/\\\/nike0good.jp1.rpvhost.net\\\/wp-content\\\/uploads\\\/csdn\\\/other_site\\\/img_my_1358819035_4823.png\",\"keywords\":[\"\u51f8\u5305\"],\"articleSection\":[\"DefaultCategory\"],\"inLanguage\":\"zh-Hans\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\\\/\\\/nike0good.com\\\/?p=314#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314\",\"url\":\"https:\\\/\\\/nike0good.com\\\/?p=314\",\"name\":\"POJ 1228(\u7a33\u5b9a\u51f8\u5305) - nike0good\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/nike0good.com\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314#primaryimage\"},\"thumbnailUrl\":\"http:\\\/\\\/nike0good.jp1.rpvhost.net\\\/wp-content\\\/uploads\\\/csdn\\\/other_site\\\/img_my_1358819035_4823.png\",\"datePublished\":\"2013-01-22T01:41:00+00:00\",\"author\":{\"@id\":\"https:\\\/\\\/nike0good.com\\\/#\\\/schema\\\/person\\\/4defa38da89de87e400861e73396baad\"},\"breadcrumb\":{\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314#breadcrumb\"},\"inLanguage\":\"zh-Hans\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/nike0good.com\\\/?p=314\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"zh-Hans\",\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314#primaryimage\",\"url\":\"http:\\\/\\\/nike0good.jp1.rpvhost.net\\\/wp-content\\\/uploads\\\/csdn\\\/other_site\\\/img_my_1358819035_4823.png\",\"contentUrl\":\"http:\\\/\\\/nike0good.jp1.rpvhost.net\\\/wp-content\\\/uploads\\\/csdn\\\/other_site\\\/img_my_1358819035_4823.png\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/nike0good.com\\\/?p=314#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/nike0good.com\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"POJ 1228(\u7a33\u5b9a\u51f8\u5305)\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/nike0good.com\\\/#website\",\"url\":\"https:\\\/\\\/nike0good.com\\\/\",\"name\":\"nike0good\",\"description\":\"\u6709\u6240\u4f5c\u4e3a\u662f\u4eba\u751f\u7684\u6700\u9ad8\u5883\u754c\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/nike0good.com\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"zh-Hans\"},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/nike0good.com\\\/#\\\/schema\\\/person\\\/4defa38da89de87e400861e73396baad\",\"name\":\"nike0good\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"zh-Hans\",\"@id\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/8e5fa08d5c367a1a6fb5ff13bb10ed5a331f981513256951290ae42322da6854?s=96&d=identicon&r=g\",\"url\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/8e5fa08d5c367a1a6fb5ff13bb10ed5a331f981513256951290ae42322da6854?s=96&d=identicon&r=g\",\"contentUrl\":\"https:\\\/\\\/secure.gravatar.com\\\/avatar\\\/8e5fa08d5c367a1a6fb5ff13bb10ed5a331f981513256951290ae42322da6854?s=96&d=identicon&r=g\",\"caption\":\"nike0good\"},\"sameAs\":[\"https:\\\/\\\/nike0good.com\"],\"url\":\"https:\\\/\\\/nike0good.com\\\/?author=1\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"POJ 1228(\u7a33\u5b9a\u51f8\u5305) - nike0good","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/nike0good.com\/?p=314","og_locale":"zh_CN","og_type":"article","og_title":"POJ 1228(\u7a33\u5b9a\u51f8\u5305) - nike0good","og_description":"Language: Default Grandpa's Estate Time Limit: 100 […]","og_url":"https:\/\/nike0good.com\/?p=314","og_site_name":"nike0good","article_published_time":"2013-01-22T01:41:00+00:00","og_image":[{"url":"http:\/\/nike0good.jp1.rpvhost.net\/wp-content\/uploads\/csdn\/other_site\/img_my_1358819035_4823.png","type":"","width":"","height":""}],"author":"nike0good","twitter_card":"summary_large_image","twitter_misc":{"\u4f5c\u8005":"nike0good","\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4":"2 \u5206"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/nike0good.com\/?p=314#article","isPartOf":{"@id":"https:\/\/nike0good.com\/?p=314"},"author":{"name":"nike0good","@id":"https:\/\/nike0good.com\/#\/schema\/person\/4defa38da89de87e400861e73396baad"},"headline":"POJ 1228(\u7a33\u5b9a\u51f8\u5305)","datePublished":"2013-01-22T01:41:00+00:00","mainEntityOfPage":{"@id":"https:\/\/nike0good.com\/?p=314"},"wordCount":54,"commentCount":0,"image":{"@id":"https:\/\/nike0good.com\/?p=314#primaryimage"},"thumbnailUrl":"http:\/\/nike0good.jp1.rpvhost.net\/wp-content\/uploads\/csdn\/other_site\/img_my_1358819035_4823.png","keywords":["\u51f8\u5305"],"articleSection":["DefaultCategory"],"inLanguage":"zh-Hans","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/nike0good.com\/?p=314#respond"]}]},{"@type":"WebPage","@id":"https:\/\/nike0good.com\/?p=314","url":"https:\/\/nike0good.com\/?p=314","name":"POJ 1228(\u7a33\u5b9a\u51f8\u5305) - nike0good","isPartOf":{"@id":"https:\/\/nike0good.com\/#website"},"primaryImageOfPage":{"@id":"https:\/\/nike0good.com\/?p=314#primaryimage"},"image":{"@id":"https:\/\/nike0good.com\/?p=314#primaryimage"},"thumbnailUrl":"http:\/\/nike0good.jp1.rpvhost.net\/wp-content\/uploads\/csdn\/other_site\/img_my_1358819035_4823.png","datePublished":"2013-01-22T01:41:00+00:00","author":{"@id":"https:\/\/nike0good.com\/#\/schema\/person\/4defa38da89de87e400861e73396baad"},"breadcrumb":{"@id":"https:\/\/nike0good.com\/?p=314#breadcrumb"},"inLanguage":"zh-Hans","potentialAction":[{"@type":"ReadAction","target":["https:\/\/nike0good.com\/?p=314"]}]},{"@type":"ImageObject","inLanguage":"zh-Hans","@id":"https:\/\/nike0good.com\/?p=314#primaryimage","url":"http:\/\/nike0good.jp1.rpvhost.net\/wp-content\/uploads\/csdn\/other_site\/img_my_1358819035_4823.png","contentUrl":"http:\/\/nike0good.jp1.rpvhost.net\/wp-content\/uploads\/csdn\/other_site\/img_my_1358819035_4823.png"},{"@type":"BreadcrumbList","@id":"https:\/\/nike0good.com\/?p=314#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/nike0good.com\/"},{"@type":"ListItem","position":2,"name":"POJ 1228(\u7a33\u5b9a\u51f8\u5305)"}]},{"@type":"WebSite","@id":"https:\/\/nike0good.com\/#website","url":"https:\/\/nike0good.com\/","name":"nike0good","description":"\u6709\u6240\u4f5c\u4e3a\u662f\u4eba\u751f\u7684\u6700\u9ad8\u5883\u754c","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/nike0good.com\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"zh-Hans"},{"@type":"Person","@id":"https:\/\/nike0good.com\/#\/schema\/person\/4defa38da89de87e400861e73396baad","name":"nike0good","image":{"@type":"ImageObject","inLanguage":"zh-Hans","@id":"https:\/\/secure.gravatar.com\/avatar\/8e5fa08d5c367a1a6fb5ff13bb10ed5a331f981513256951290ae42322da6854?s=96&d=identicon&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/8e5fa08d5c367a1a6fb5ff13bb10ed5a331f981513256951290ae42322da6854?s=96&d=identicon&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/8e5fa08d5c367a1a6fb5ff13bb10ed5a331f981513256951290ae42322da6854?s=96&d=identicon&r=g","caption":"nike0good"},"sameAs":["https:\/\/nike0good.com"],"url":"https:\/\/nike0good.com\/?author=1"}]}},"_links":{"self":[{"href":"https:\/\/nike0good.com\/index.php?rest_route=\/wp\/v2\/posts\/314","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nike0good.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nike0good.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nike0good.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nike0good.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=314"}],"version-history":[{"count":0,"href":"https:\/\/nike0good.com\/index.php?rest_route=\/wp\/v2\/posts\/314\/revisions"}],"wp:attachment":[{"href":"https:\/\/nike0good.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=314"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nike0good.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=314"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nike0good.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=314"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}