{"id":114,"date":"2025-01-11T23:41:58","date_gmt":"2025-01-11T15:41:58","guid":{"rendered":"http:\/\/150.230.63.147\/blog\/?p=114"},"modified":"2025-01-11T23:41:58","modified_gmt":"2025-01-11T15:41:58","slug":"d-number-of-parallelograms-%e8%a7%a3%e6%9e%90%e5%b9%be%e4%bd%95","status":"publish","type":"post","link":"https:\/\/blog.seekrealthing.net\/blog\/?p=114","title":{"rendered":"D. Number of Parallelograms \u89e3\u6790(\u5e7e\u4f55)"},"content":{"rendered":"\n

Codeforce 660 D. Number of Parallelograms \u89e3\u6790(\u5e7e\u4f55)<\/h1>\n

\u4eca\u5929\u6211\u5011\u4f86\u770b\u770bCF660D
\n\u984c\u76ee\u9023\u7d50<\/a><\/p>\n

\n

\u984c\u76ee<\/strong>
\n\u7d66\u4f60\u4e00\u4e9b\u9ede\uff0c\u6c42\u6709\u591a\u5c11\u500b\u5e73\u884c\u56db\u908a\u5f62\u3002<\/p>\n<\/blockquote>\n

\u524d\u8a00<\/h3>\n

a<\/p>\n

\u60f3\u6cd5<\/h3>\n

\u6ce8\u610f\u5230\uff0c\u53ea\u8981\u6709\u5169\u500b\u7b49\u9577\u7684\u5e73\u884c\u908a\uff0c\u90a3\u6211\u5011\u5c31\u627e\u5230\u4e86\u4e00\u500b\u5e73\u884c\u56db\u908a\u5f62\u4e86\u3002
\n\u6240\u4ee5\u53ea\u8981\u7528\u4e00\u500b$map$\u7d00\u9304\u6bcf\u500b\u7dda\u6bb5\u51fa\u73fe\u7684\u6b21\u6578\uff0c\u4e14\u6bcf\u6b21\u52a0\u5165\u4e00\u500b\u7dda\u6bb5(\u6211\u5011\u679a\u8209\u7dda\u6bb5)\u6642\uff0c\u5148\u628a\u7b54\u6848\u52a0\u4e0a\u76ee\u524d\u6709\u591a\u5c11\u7b49\u9577\u5e73\u884c\u7dda\u6bb5\uff0c\u6700\u5f8c\u7b54\u6848\u9664\u4ee5\u4e8c\u5c31\u884c\u4e86\u3002<\/p>\n

\u7a0b\u5f0f\u78bc:<\/h3>\n
const int _n=2010;  \nint t,n,x,y;  \nvector<PII> ps;  \nmap<PII,int> cnt;  \nll ans;  \nmain(void) {ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);  \n  cin>>n;rep(i,0,n){cin>>x>>y;ps.pb({x,y});}  \n  rep(i,0,n-1)rep(j,i+1,n){  \n    PII v={ps[j].fi-ps[i].fi,ps[j].se-ps[i].se};  \n    if(v.fi<0)v.fi=-v.fi,v.se=-v.se;  \n    if(v.fi==0 and v.se<0)v.se=-v.se;  \n    ans+=cnt[v]; cnt[v]++;  \n  }cout<<ans\/2<<'\\n';  \n  return 0;  \n}  \n<\/code><\/pre>\n
\u6a19\u982d\u3001\u6a21\u677f\u8acb\u9edeSubmission\u770b
\nSubmission<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_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},"version":2}},"categories":[3],"tags":[10,9,22],"class_list":["post-114","post","type-post","status-publish","format-standard","hentry","category-ojcode","tag-codeforce","tag-ojcode","tag-22"],"jetpack_publicize_connections":[],"yoast_head":"\nD. 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