{"id":53787,"date":"2025-08-12T17:10:04","date_gmt":"2025-08-12T09:10:04","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/53787.html"},"modified":"2025-08-12T17:10:04","modified_gmt":"2025-08-12T09:10:04","slug":"p2899-usaco08jan-cell-phone-network-g-%e6%a0%91%e5%9e%8bdp","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/53787.html","title":{"rendered":"P2899 [USACO08JAN] Cell Phone Network G (\u6811\u578bdp)"},"content":{"rendered":"

\u6d4b\u8bd5\u94fe\u63a5<\/p>\n

\u9898\u76ee\u63cf\u8ff0<\/h3>\n

Farmer John \u60f3\u8ba9\u4ed6\u7684\u6240\u6709\u725b\u7528\u4e0a\u624b\u673a\u4ee5\u4fbf\u76f8\u4e92\u4ea4\u6d41\u3002\u4ed6\u9700\u8981\u5efa\u7acb\u51e0\u5ea7\u4fe1\u53f7\u5854\u5728 <\/p>\n

N<\/p>\n

N<\/p>\n

<\/span><\/span>N<\/span><\/span><\/span><\/span><\/span> \u5757\u8349\u5730\u4e2d\u3002\u5df2\u77e5\u4e0e\u4fe1\u53f7\u5854\u76f8\u90bb\u7684\u8349\u5730\u80fd\u6536\u5230\u4fe1\u53f7\u3002\u7ed9\u4f60 <\/p>\n

N<\/p>\n

\u2212<\/p>\n

1<\/p>\n

N-1<\/p>\n

<\/span><\/span>N<\/span><\/span>\u2212<\/span><\/span><\/span><\/span>1<\/span><\/span><\/span><\/span><\/span> \u4e2a\u8349\u5730 <\/p>\n

(<\/p>\n

A<\/p>\n

,<\/p>\n

B<\/p>\n

)<\/p>\n

(A,B)<\/p>\n

<\/span><\/span>(<\/span>A<\/span>,<\/span><\/span>B<\/span>)<\/span><\/span><\/span><\/span><\/span> \u7684\u76f8\u90bb\u5173\u7cfb，\u95ee：\u6700\u5c11\u9700\u8981\u5efa\u591a\u5c11\u4e2a\u4fe1\u53f7\u5854\u80fd\u5b9e\u73b0\u6240\u6709\u8349\u5730\u90fd\u6709\u4fe1\u53f7\u3002<\/p>\n

\u8f93\u5165\u683c\u5f0f<\/h3>\n

\u7b2c <\/p>\n

1<\/p>\n

1<\/p>\n

<\/span><\/span>1<\/span><\/span><\/span><\/span><\/span> \u884c：\u4e00\u4e2a\u6574\u6570 <\/p>\n

N<\/p>\n

N<\/p>\n

<\/span><\/span>N<\/span><\/span><\/span><\/span><\/span>\u3002<\/p>\n

\u7b2c <\/p>\n

2<\/p>\n

2<\/p>\n

<\/span><\/span>2<\/span><\/span><\/span><\/span><\/span> \u884c\u5230\u7b2c <\/p>\n

N<\/p>\n

N<\/p>\n

<\/span><\/span>N<\/span><\/span><\/span><\/span><\/span> \u884c：\u6bcf\u4e00\u884c\u4e24\u4e2a\u6574\u6570，\u7528\u7a7a\u683c\u5206\u9694，\u7ed9\u51fa\u4e00\u5bf9\u76f8\u90bb\u7684\u8349\u5730 <\/p>\n

A<\/p>\n

A<\/p>\n

<\/span><\/span>A<\/span><\/span><\/span><\/span><\/span> \u548c <\/p>\n

B<\/p>\n

B<\/p>\n

<\/span><\/span>B<\/span><\/span><\/span><\/span><\/span>\u3002<\/p>\n

\u8f93\u51fa\u683c\u5f0f<\/h3>\n

\u4e00\u4e2a\u6574\u6570，\u8868\u793a\u8981\u5b89\u88c5\u7684\u6700\u5c11\u4fe1\u53f7\u5854\u6570\u3002<\/p>\n

\u8f93\u5165\u8f93\u51fa\u6837\u4f8b #1<\/h3>\n

\u8f93\u5165 #1<\/h4>\n

5
\n1 3
\n5 2
\n4 3
\n3 5<\/p>\n

\u8f93\u51fa #1<\/h4>\n

2<\/p>\n

\u8bf4\u660e\/\u63d0\u793a<\/h3>\n

\u5bf9\u4e8e\u6240\u6709\u7684\u6570\u636e，<\/p>\n

1<\/p>\n

\u2264<\/p>\n

N<\/p>\n

\u2264<\/p>\n

10<\/p>\n

4<\/p>\n

1 \\\\leq N \\\\leq 10^4<\/p>\n

<\/span><\/span>1<\/span><\/span>\u2264<\/span><\/span><\/span><\/span>N<\/span><\/span>\u2264<\/span><\/span><\/span><\/span>1<\/span>0<\/span><\/span>4<\/span><\/span><\/span><\/span><\/span><\/span><\/span><\/span><\/span><\/span><\/span><\/span>，<\/p>\n

1<\/p>\n

\u2264<\/p>\n

A<\/p>\n

,<\/p>\n

B<\/p>\n

\u2264<\/p>\n

N<\/p>\n

1 \\\\leq A,B \\\\leq N<\/p>\n

<\/span><\/span>1<\/span><\/span>\u2264<\/span><\/span><\/span><\/span>A<\/span>,<\/span><\/span>B<\/span><\/span>\u2264<\/span><\/span><\/span><\/span>N<\/span><\/span><\/span><\/span><\/span>，<\/p>\n

A<\/p>\n

\u2260<\/p>\n

B<\/p>\n

A \\\\neq B<\/p>\n

<\/span><\/span>A<\/span><\/span><\/span>\ue020<\/span><\/span><\/span><\/span><\/span><\/span><\/span><\/span>=<\/span><\/span><\/span><\/span><\/span>B<\/span><\/span><\/span><\/span><\/span>\u3002<\/p>\n

\u601d\u8def<\/h3>\n

\u4e0eleedcode968 \u76d1\u63a7\u4e8c\u53c9\u6811\u7684\u601d\u8def\u7c7b\u4f3c，\u8d2a\u5fc3+\u6811\u578bdp，\u5206\u7c7b\u8ba8\u8bba<\/p>\n

\u9898\u89e3<\/h3>\n

#include <bits\/stdc++.h>
\nconst int N = 1e4+10;
\nusing namespace std;
\nvector<int>graph[N];
\nint ans=0;
\nint n;<\/p>\n

int f(int u,int p)
\n{
\n bool s0= false;
\n bool s2 = false;
\n for(auto v:graph[u])
\n {
\n if(v==p)continue;
\n int cs = f(v,u);
\n if(cs==2)s2 = true;
\n else if(cs==0)s0=true;
\n }
\n if(s0)
\n {
\n ans++;
\n return 2;
\n }
\n if(s2)
\n {
\n return 1;
\n }
\n return 0;
\n}<\/p>\n

int main()
\n{
\n cin>>n;
\n for(int i=1;i<n;i++)
\n {
\n int f,t;
\n cin>>f>>t;
\n graph[f].push_back(t);
\n graph[t].push_back(f);
\n }
\n if(n==1)
\n {
\n cout<<1<<endl;
\n return 0;
\n }
\n if(f(1,0)==0)ans++;
\n cout<<ans<<endl;<\/p>\n

return 0;
\n}<\/p>\n","protected":false},"excerpt":{"rendered":"

\u6587\u7ae0\u6d4f\u89c8\u9605\u8bfb25\u6b21\u3002\u6d1b\u8c37 P2899 \u9898\u89e3<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[55,2865,3509,5478,5477],"topic":[],"class_list":["post-53787","post","type-post","status-publish","format-standard","hentry","category-server","tag-c","tag-2865","tag-3509","tag-dp","tag-5477"],"yoast_head":"\nP2899 [USACO08JAN] Cell Phone Network G (\u6811\u578bdp) - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3<\/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:\/\/www.wsisp.com\/helps\/53787.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"P2899 [USACO08JAN] Cell Phone Network G (\u6811\u578bdp) - 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