LCA(最近公共祖先)模板

/*  gyt
Live up to every day            */
#pragma comment(linker,"/STACK:1024000000,1024000000")
#include<cstdio>
#include<cmath>
#include<iostream>
#include<algorithm>
#include<vector>
#include<stack>
#include<cstring>
#include<queue>
#include<set>
#include<string>
#include<map>
#include <time.h>
#define PI acos(-1)
using namespace std;
typedef long long ll;
typedef double db;
const int maxn = 1e5+5;
const ll maxm = 1e7;
const ll base = 2333;
const int INF = 1<<30;
const db eps = 1e-8;
const ll mod = 1e9+7;
struct Edge{
int u, v, next, val;
}edge[maxn*2], edge1[maxn*2];
int n, m;
int head[maxn], head1[maxn];
int father[maxn], dis[maxn], tol, toll, LCA[maxn];
bool visit[maxn];
int cnt;
//LCA[]最近公共祖先

void init() {
cnt=0;
memset(head, -1, sizeof(head));
memset(head1, -1, sizeof(head1));
tol=toll=0;
memset(visit, 0, sizeof(visit));
memset(LCA, 0, sizeof(LCA));
memset(dis, 0, sizeof(dis));
}
void add(int u, int v, int w) {
edge[tol].u=u, edge[tol].v=v,edge[tol].val=w;
edge[tol].next=head[u];
head[u]=tol++;
}
void add1(int u, int v, int w) {
edge1[toll].u=u, edge1[toll].v=v,edge1[toll].val=w;
edge1[toll].next=head1[u];
head1[u]=toll++;
}
int Find(int x) {
if (x!=father[x])  father[x]=Find(father[x]);
return father[x];
}
void tarjan(int u) {
visit[u]=1;
father[u]=u;
for (int j=head1[u]; ~j; j=edge1[j].next) {
int v=edge1[j].v;
if (visit[v])  LCA[edge1[j].val]=Find(v);
}
for (int j=head[u]; ~j; j=edge[j].next) {
int v=edge[j].v;
if (!visit[v]) {
dis[v]=dis[u]+edge[j].val;
tarjan(v);
father[v]=u;
//cout<<dis[v]<<endl;
}
}
}
void solve() {
init();
scanf("%d%d", &n, &m);
for (int i=1; i<n; i++) {
int a, b, c;  scanf("%d%d%d", &a, &b, &c);
add(a, b, c);  add(b, a, c);
}
for (int i=0; i<m; i++) {
int a, b;  scanf("%d%d", &a, &b);
add1(a, b, i);  add1(b, a, i);
}
dis[1]=0;
tarjan(1);
for(int i=0;i<toll;i+=2){
printf("%d\n",LCA[edge1[i].val]);
}
}
int main() {
int t = 1;
//freopen("in.txt","r",stdin);
//  freopen("gcd.out","w",stdout);
scanf("%d", &t);
while(t--)
solve();
return 0;
}

/*  gyt
Live up to every day            */
#pragma comment(linker,"/STACK:1024000000,1024000000")
#include<cstdio>
#include<cmath>
#include<iostream>
#include<algorithm>
#include<vector>
#include<stack>
#include<cstring>
#include<queue>
#include<set>
#include<string>
#include<map>
#include <time.h>
#define PI acos(-1)
using namespace std;
typedef long long ll;
typedef double db;
const int maxn = 1e5+5;
const ll maxm = 1e7;
const ll base = 2333;
const int INF = 1<<30;
const db eps = 1e-8;
const ll mod = 1e9+7;
struct Edge{
int u, v, next, val;
}edge[maxn*2];
int head[maxn], dis[maxn];
int f[maxn], deep[maxn], p[maxn][20];
int n, m, cnt;

void init() {
int i,j;
for(j=0;(1<<j)<=n;j++)
for(i=1;i<=n;i++)
p[i][j]=-1;
for(i=1;i<=n;i++)p[i][0]=f[i];
for(j=1;(1<<j)<=n;j++)
for(i=1;i<=n;i++)
if(p[i][j-1]!=-1)
p[i][j]=p[p[i][j-1]][j-1];//i的第2^j祖先就是i的第2^(j-1)祖先的第2^(j-1)祖先
}
void add(int u, int v, int w) {
edge[cnt].u=u, edge[cnt].v=v;
edge[cnt].next=head[u], edge[cnt].val=w;
head[u]=cnt++;
}
void dfs(int u, int pre, int t) {
deep[u]=t;
f[u]=pre;
for (int i=head[u]; ~i; i=edge[i].next) {
int v=edge[i].v;
if (v!=pre) {
dis[v]=dis[u]+edge[i].val;
dfs(v, u, t+1);
}
}
}
int lca(int a, int b) {
int i, j;
if (deep[a]<deep[b])  swap(a, b);
for ( i=0; (1<<i)<=deep[a]; i++);
i--;
for ( j=i; j>=0; j--) {
if (deep[a]-(1<<j)>=deep[b])  a=p[a][j];
}
if (a==b)  return a;
for ( j=i; j>=0; j--) {
if (p[a][j]!=-1 && p[a][j]!=p[b][j]) {
a=p[a][j], b=p[b][j];
}
}
return f[a];
}
void solve() {
scanf("%d%d", &n, &m);
cnt=0;
memset(head, -1, sizeof(head));
for (int i=0; i<n-1; i++) {
int a, b, c;  scanf("%d%d%d", &a, &b, &c);
add(a, b, c);  add(b, a, c);
}
dis[1]=0;
dfs(1, -1, 0);
init();
for (int i=0; i<m; i++) {
int a, b;  scanf("%d%d", &a, &b);
int ans=dis[a]+dis[b]-2*dis[lca(a, b)];
printf("%d\n", ans);
}
}
int main() {
int t = 1;
// freopen("in.txt","r",stdin);
//  freopen("gcd.out","w",stdout);
scanf("%d", &t);
while(t--)
solve();
return 0;
}