【hdu2586】How far away? lca

题意：给棵树询问树上两点距离

 

lca 板子

 

 

#include
#include
#include
#include
#define lim 80500
using namespace std;

int T,n,m,tot;
int f[lim][31],v[lim],c[lim],head[lim],nextt[lim],dist[lim],depth[lim];

void add_edge(int x,int y,int z){v[++tot]=y;c[tot]=z;nextt[tot]=head[x];head[x]=tot;}
void init()
{
    for (int i=0;i<=n;i++)
    {
        tot=0;c[i]=0;v[i]=0;head[i]=0;nextt[i]=0;dist[i]=0;depth[i]=0;
        for (int j=0;j<31;j++) f[i][j]=0;
    }
}
void dfs(int x,int g)
{
    for (int i=head[x];i;i=nextt[i])
    {
        int y=v[i];
        if (y!=g)
        {
            depth[y]=depth[x]+1;
            dist[y]=dist[x]+c[i];
            f[y][0]=x;
            for (int j=1;j<31;j++) f[y][j]=f[f[y][j-1]][j-1];
            dfs(y,x);
        }
    }
}
int lca(int x,int y)
{
    if (depth[x]=0;i--)
        if (f[x][i]!=f[y][i]) x=f[x][i],y=f[y][i];
    return (x==y?x:f[x][0]);
}

int main()
{
    scanf("%d",&T);
    while(T--)
    {
        int x,y,z;
        scanf("%d%d",&n,&m);
        init();
        for (int i=0;i