Time
Limit: 10000/5000 MS (Java/Others) Memory Limit:
32768/32768 K (Java/Others)
Total Submission(s):
3937 Accepted Submission(s):
1144
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<string>
#include<queue>
#include<vector>
#include<stdlib.h>
#include<set>
#include<map>
#include<cmath>
using namespace std;
#define maxn 10000+5
int pre[maxn][20],vit[maxn],n,m,c,deep[maxn];
__int64 lenth[maxn][20];
vector<int >ko[maxn],dis[maxn];
void dfs(int x,int de)
{
vit[x]=1;
deep[x]=de;
for(int i=0; i<ko[x].size(); i++)
{
int to=ko[x][i];
if(!vit[to])
{
pre[to][0]=x;
lenth[to][0]=dis[x][i];
dfs(to,de+1);
}
}
}
int main()
{
int i,j;
while(cin>>n>>m>>c)
{
for(i=1; i<=n; i++)
{
ko[i].clear();
dis[i].clear();
}
for(i=1; i<=m; i++)
{
int u,v,l;
scanf("%d%d%d",&u,&v,&l);
ko[u].push_back(v);
dis[u].push_back(l);
ko[v].push_back(u);
dis[v].push_back(l);
}
memset(vit,0,sizeof(vit));
memset(pre,-1,sizeof(pre));
memset(lenth,0,sizeof(lenth));
memset(deep,0,sizeof(deep));
for(i=1; i<=n; i++)
if(!vit[i])
{
pre[i][0]=0;
dfs(i,1);
}
for(i=1; i<20; i++)
for(j=1; j<=n; j++)
{
if(pre[j][i-1]!=-1)
{
pre[j][i]=pre[ pre[j][i-1] ][i-1];
lenth[j][i]=lenth[j][i-1]+lenth[ pre[j][i-1] ][i-1];
}
}
while(c--)
{
int u,v,dd,num=0;
__int64 mm=0;
scanf("%d%d",&u,&v);
if(deep[u]<deep[v]) swap(u,v);
dd=deep[u]-deep[v];
while(dd) //使 u v处于同一点
{
if(dd&1)
{
mm+=lenth[u][num];
u=pre[u][num];
}
++num;
dd>>=1;
}
if(u==v)
{
if(u>0)
printf("%I64d\n",mm);
else
printf("Not connected\n");
continue;
}
while(u!=v)
{
int If;
for(i=0; i<20; i++)
{
if(pre[u][i]==pre[v][i])
{
If=i;
break;
}
}
if(If==0)
{
if(pre[u][0]>0)
{
mm+=lenth[u][0]+lenth[v][0];
printf("%I64d\n",mm);
}
else
printf("Not connected\n");
break;
}
else
{
mm+=lenth[u][If-1]+lenth[v][If-1];
u=pre[u][If-1];
v=pre[v][If-1];
}
}
}
}
}
Lca hdu 2874 Connections between cities,布布扣,bubuko.com
Lca hdu 2874 Connections between cities
原文:http://www.cnblogs.com/ainixu1314/p/3608730.html