{"id":119,"date":"2010-02-22T03:39:00","date_gmt":"2010-02-21T19:39:00","guid":{"rendered":"http:\/\/localhost\/?p=119"},"modified":"2010-02-22T03:39:00","modified_gmt":"2010-02-21T19:39:00","slug":"spoj_3978_distance_query","status":"publish","type":"post","link":"https:\/\/www.shuizilong.com\/wjmzbmr\/?p=119","title":{"rendered":"SPOJ 3978 Distance Query"},"content":{"rendered":"

Link\uff1aProblem<\/a>
\u5927\u610f\u662f\u7ed9\u4e00\u9897\u4ee3\u6743\u6811\u3002Q\u4e2a\u8be2\u95ee\u3002\u6bcf\u4e2a\u8be2\u95ee\u662f\u4e24\u4e2a\u8282\u70b9\u3002
\u8ba9\u4f60\u56de\u7b54\u8fd9\u4e24\u4e2a\u8282\u70b9\u4e4b\u95f4\u8def\u5f84\u4e0a\u7684\u6700\u957f\u8fb9\u548c\u6700\u77ed\u8fb9\u3002
\u8ddfPKU\u6708\u8d5b\u7684\u67d0\u9898\u6709\u70b9\u50cf\u3002
\u4f7f\u7528\u79bb\u7ebf\u7b97\u6cd5\u7c7btarjan\u7b97\u6cd5\u3002
\u5728\u5e76\u67e5\u96c6\u4e2d\u5bf9\u6bcf\u4e2a\u8282\u70b9\u7ef4\u62a4\u4e00\u4e2a\u5230\u7236\u4eb2\uff08\u5e76\u67e5\u96c6\u4e2d\u7684\u7236\u4eb2\uff09\u7684\u8def\u5f84\u4e0a\u6700\u957f\u548c\u6700\u77ed\u7684\u8fb9\u3002\u3002
\u90a3\u4e48\u5728\u8def\u5f84\u538b\u7f29\u7684\u65f6\u5019\u4e5f\u53ef\u4ee5\u987a\u4fbf\u5408\u5e76\u3002\u3002
\u5728\u6c42\u51fa\u4e24\u4e2a\u8282\u70b9\u4e4b\u95f4\u7684lca\u4e4b\u540e\u3002\u3002\u7b49dfs\u56de\u5230\u4e86\u8fd9\u4e2alca\u3002\u3002\u5c31\u6709\u5145\u5206\u7684\u4fe1\u606f\u4e86\u3002\u3002
\u53ef\u4ee5\u5f88\u65b9\u4fbf\u7684\u8ba1\u7b97\u7b54\u6848
PS\u6211\u592a\u4f9d\u8d56stl\u4e86\u3002\u3002\u8fd9\u6837\u4e0b\u53bb\u600e\u4e48\u884c
Code\uff1a<\/p>\n

#include<cstdio>
#include<vector>
#include<algorithm>
#include<iostream>
#define pb push_back
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
const int inf=~0U>>1;
const int maxn=100000;int n;
const int maxm=maxn;int m;
struct edge
{
int t,c;
edge(int _t,int _c):t(_t),c(_c){}
};
struct queryLca
{
int t,n;
queryLca(int _t,int _n):t(_t),n(_n){}
};
struct query
{
int a,b,n;
query(int _a,int _b,int _n):a(_a),b(_b),n(_n){}
};
struct info
{
int Min,Max;
info():Min(inf),Max(-inf){}
info(int v):Min(v),Max(v){}
void print() const{cout<<"{"<<Min<<","<<Max<<"}";}
void Merge(const info& o)
{
\/\/print();cout<<" + ";o.print();cout<<endl;
Min=min(Min,o.Min);
Max=max(Max,o.Max);
}
};
vector<edge> E[maxn];
vector<queryLca> Lca[maxn];
vector<query> Query[maxn];
typedef vector<edge>::iterator eit;
typedef vector<queryLca>::iterator lit;
typedef vector<query>::iterator qit;
info Ans[maxm];
void add_edge(int s,int t,int c)
{
E[s].pb(edge(t,c));
E[t].pb(edge(s,c));
}
void add_lca(int s,int t,int n)
{
Lca[s].pb(queryLca(t,n));
Lca[t].pb(queryLca(s,n));
}
info P[maxn];
int F[maxn];
void set()
{
rep(i,n) F[i]=i;
}
int find(int x)
{
int tmp=F[x];
if(F[x]!=x)
F[x]=find(F[x]),P[x].Merge(P[tmp]);
return F[x];
}
void Union(int i,int j,int c)
{
F[j]=i;
P[j]=info(c);
}
bool vis[maxn]={0};
void dfs(int x)
{
vis[x]=true;\/\/cout<<x<<endl;
for(eit i=E[x].begin();i!=E[x].end();i++)if(!vis[i->t])
dfs(i->t),Union(x,i->t,i->c);
for(lit i=Lca[x].begin();i!=Lca[x].end();i++)
{
if(vis[i->t])
{
Query[find(i->t)].pb(query(x,i->t,i->n));
\/\/cout<<find(i->t)<<" "<<x<<" "<<i->t<<endl;
}
}
for(qit i=Query[x].begin();i!=Query[x].end();i++)
{
find(i->a);find(i->b);
info&x=Ans[i->n];
x=P[i->a];x.Merge(P[i->b]);
}
}
void init()
{
scanf("%d",&n);int s,t,c;
set();
for(int i=0;i<n-1;i++)
{
scanf("%d %d %d",&s,&t,&c);
add_edge(s-1,t-1,c);
}
scanf("%d",&m);int a,b;
for(int i=0;i<m;i++)
{
scanf("%d %d",&a,&b);
add_lca(a-1,b-1,i);
}
}
void solve()
{
dfs(0);
for(int i=0;i<m;i++)
printf("%d %dn",Ans[i].Min,Ans[i].Max);
}
int main()
{
\/\/freopen("in","r",stdin);
\/\/freopen("out","w",stdout);
init();
solve();
}
\u672c\u9ad8\u4eae\u4ee3\u7801\u4f7f\u7528codeHl\u751f\u6210\uff0c
\u8bdd\u8bf4\u62113\u70b9\u534a\u4e86\u95f2\u7740\u65e0\u804a\u5c45\u7136\u5f00\u59cb\u5237\u9898\u4e86\u3002\u3002 <\/p>\n","protected":false},"excerpt":{"rendered":"

Link\uff1aProblem\u5927\u610f\u662f\u7ed9\u4e00\u9897\u4ee3\u6743\u6811\u3002Q\u4e2a\u8be2\u95ee\u3002\u6bcf\u4e2a\u8be2\u95ee\u662f\u4e24\u4e2a\u8282\u70b9\u3002\u8ba9\u4f60\u56de\u7b54\u8fd9\u4e24\u4e2a\u8282\u70b9\u4e4b\u95f4\u8def\u5f84\u4e0a\u7684\u6700\u957f\u8fb9\u548c\u6700\u77ed\u8fb9\u3002\u8ddfPKU\u6708\u8d5b\u7684\u67d0\u9898\u6709\u70b9\u50cf\u3002\u4f7f\u7528\u79bb\u7ebf\u7b97\u6cd5\u7c7btarjan\u7b97\u6cd5\u3002\u5728\u5e76\u67e5\u96c6\u4e2d\u5bf9\u6bcf\u4e2a\u8282\u70b9\u7ef4\u62a4\u4e00\u4e2a\u5230\u7236\u4eb2\uff08\u5e76\u67e5\u96c6\u4e2d\u7684\u7236\u4eb2\uff09\u7684\u8def\u5f84\u4e0a\u6700\u957f\u548c\u6700\u77ed\u7684\u8fb9\u3002\u3002\u90a3\u4e48\u5728\u8def\u5f84\u538b\u7f29\u7684\u65f6\u5019\u4e5f\u53ef\u4ee5\u987a\u4fbf\u5408\u5e76\u3002\u3002\u5728\u6c42\u51fa\u4e24\u4e2a\u8282\u70b9\u4e4b\u95f4\u7684lca\u4e4b\u540e\u3002\u3002\u7b49dfs\u56de\u5230\u4e86\u8fd9\u4e2alca\u3002\u3002\u5c31\u6709\u5145\u5206\u7684\u4fe1\u606f\u4e86\u3002\u3002\u53ef\u4ee5\u5f88\u65b9\u4fbf\u7684\u8ba1\u7b97\u7b54\u6848PS\u6211\u592a\u4f9d\u8d56stl\u4e86\u3002\u3002\u8fd9\u6837\u4e0b\u53bb\u600e\u4e48\u884cCode\uff1a #include<cstdio>#include<vector>#include<algorithm>#include<iostream>#define pb push_back#define rep(i,n) for(int i=0;i<n;i++)using namespace std;const int inf=~0U>>1;const int maxn=100000;int n;const int maxm=maxn;int m;struct edge{ int t,c; edge(int _t,int _c):t(_t),c(_c){}};struct queryLca{ int t,n; queryLca(int _t,int _n):t(_t),n(_n){}};struct query{ int a,b,n; query(int _a,int _b,int _n):a(_a),b(_b),n(_n){}};struct info{ int Min,Max; info():Min(inf),Max(-inf){} info(int v):Min(v),Max(v){} void print() const{cout<<"{"<<Min<<","<<Max<<"}";} void Merge(const info& o) { \/\/print();cout<<" + ";o.print();cout<<endl; Min=min(Min,o.Min); Max=max(Max,o.Max); […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[10],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/119"}],"collection":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=119"}],"version-history":[{"count":0,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/119\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=119"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=119"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=119"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}