Ax+By+C=0\u00a0<\/span><\/span><\/span>\u7684\u8ddd\u79bb\u7684\u5e73\u65b9\u516c\u5f0f\u662f<\/p>\n![\"\"](\"http:\/\/kylelv.com\/wp-content\/uploads\/2018\/01\/QQ\u622a\u56fe20180116210435.jpg\")
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\u7136\u540e\u5c31\u6c42\u4e00\u4e0b\u504f\u5bfc\u7b97\u4e00\u4e0b\u5c31\u597d\u4e86\uff0c\u5269\u4e0b\u5c31\u662f\u7ec6\u8282\u95ee\u9898\u4e86<\/p>\n
#include<map>\r\n#include<cmath>\r\n#include<queue>\r\n#include<cstdio>\r\n#include<cstring>\r\n#include<iostream>\r\n#include<algorithm>\r\nusing namespace std;\r\n#define inf 1000000007\r\n#define ll long long\r\n#define N 120010\r\n#define db double\r\nstruct qaz{db a,b,c;}a[N];\r\nint n,tot,ji;\r\ndb x,y,xx,yy;\r\ndb A,B,C,D,E,F;\r\nvoid ins()\r\n{\r\n\tint p=++tot;ji++;\r\n\ta[p].a=y-yy;a[p].b=xx-x;a[p].c=y*(x-xx)-x*(y-yy);\r\n\tdb tp=(a[p].a*a[p].a+a[p].b*a[p].b);\r\n\tA+=a[p].a*a[p].a\/tp;B+=a[p].b*a[p].b\/tp;\r\n\tC+=2*a[p].a*a[p].b\/tp;D+=2*a[p].a*a[p].c\/tp;\r\n\tE+=2*a[p].b*a[p].c\/tp;F+=a[p].c*a[p].c\/tp;\r\n}\r\nvoid del(int p)\r\n{\r\n\tji--;db tp=(a[p].a*a[p].a+a[p].b*a[p].b);\r\n\tA-=a[p].a*a[p].a\/tp;B-=a[p].b*a[p].b\/tp;\r\n\tC-=2*a[p].a*a[p].b\/tp;D-=2*a[p].a*a[p].c\/tp;\r\n\tE-=2*a[p].b*a[p].c\/tp;F-=a[p].c*a[p].c\/tp;\r\n}\r\ndb ans,f[3][4];\r\n#define eps 1e-5\r\nvoid sol()\r\n{\r\n\tf[1][1]=2*A;f[1][2]=C;f[1][3]=-D;\r\n\tf[2][1]=C;f[2][2]=2*B;f[2][3]=-E;\r\n\tdb tx,ty,tt;\r\n\tif(abs(f[1][1])<eps)\r\n\t{\r\n\t\tif(abs(f[1][2])<eps) tx=0,ty=f[2][3]\/f[2][2];\r\n\t\telse ty=f[1][3]\/f[1][2],tx=(f[2][3]-f[2][2]*ty)\/f[2][1];\r\n\t}\r\n\telse if(abs(f[2][2])<eps)\r\n\t{\r\n\t\tif(abs(f[2][1])<eps) ty=0,tx=f[1][3]\/f[1][1];\r\n\t\telse tx=f[2][3]\/f[2][1],ty=(f[1][3]-f[1][1]*tx)\/f[1][2];\r\n\t}\r\n\telse \r\n\t{\r\n\t\ttt=f[2][1]\/f[1][1];f[2][1]=0;\r\n\t\tf[2][2]-=tt*f[1][2];f[2][3]-=tt*f[1][3];\r\n\t\tty=(abs(f[2][2])<eps)?0:f[2][3]\/f[2][2];\r\n\t\ttx=(abs(f[1][1])<eps)?0:(f[1][3]-f[1][2]*ty)\/f[1][1];\r\n\t}\r\n\tans=abs(A*tx*tx+B*ty*ty+C*tx*ty+D*tx+E*ty+F);\r\n\tif(ans<eps) puts(\"0.00\");\r\n\telse printf(\"%.2lf\\n\",ans);\r\n}\r\nint main()\r\n{\r\n\tscanf(\"%d\",&n);\r\n\tint op,p;\r\n\twhile(n--)\r\n\t{\r\n\t\tscanf(\"%d\",&op);\r\n\t\tif(!op)\r\n\t\t{\r\n\t\t\tscanf(\"%lf%lf%lf%lf\",&x,&y,&xx,&yy);\r\n\t\t\tins(); \r\n\t\t}\r\n\t\telse if(op==1)\r\n\t\t{\r\n\t\t\tscanf(\"%d\",&p);\r\n\t\t\tdel(p);\r\n\t\t}\r\n\t\telse \r\n\t\t{\r\n\t\t\tif(!ji){puts(\"0.00\");continue;}\r\n\t\t\tsol();\r\n\t\t} \r\n\t}\r\n\treturn 0;\r\n}<\/pre>\n <\/p>\n","protected":false},"excerpt":{"rendered":"
2508: \u7b80\u5355\u9898 Time Limit:\u00a010 Sec\u00a0\u00a0Memory Limit:\u00a0512 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[8],"class_list":["post-481","post","type-post","status-publish","format-standard","hentry","category-bzoj","tag-8"],"_links":{"self":[{"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=\/wp\/v2\/posts\/481","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=481"}],"version-history":[{"count":2,"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=\/wp\/v2\/posts\/481\/revisions"}],"predecessor-version":[{"id":485,"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=\/wp\/v2\/posts\/481\/revisions\/485"}],"wp:attachment":[{"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=481"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=481"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.kylelv.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=481"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}