zoj 3195 Design the city （lca,dfs+rmq）

 1#include <cstdio>
 2#include <cstring>
 3#include <iostream>
 4#include <algorithm>
 5#include <vector>
 6#include <queue>
 7#include <set>
 8#include <map>
 9#include <string>
10#include <cmath>
11#include <cstdlib>
12#include <ctime>
13#define fst first
14#define sec second
15#define lson l,m,rt<<1
16#define rson m+1,r,rt<<1|1
17#define ms(a,x) memset(a,x,sizeof(a))
18typedef long long LL;
19#define pi pair < int ,int >
20#define MP make_pair

 1using namespace std;
 2const double eps = 1E-8;
 3const int dx4[4]={1,0,0,-1};
 4const int dy4[4]={0,-1,1,0};
 5const int inf = 0x3f3f3f3f;
 6const int N=5E4+7;
 7int n,m;
 8vector < pi > edge[N];
 9int q;
10int in[N];
11int E[2*N],R[2*N],dis[N],depth[2*N];
12int p;
13int dp[2*N][20];
14void dfs( int u,int dep,int d,int pre)
15{

1  //  cout<<"u:"<<u<<" dep:"<<dep<<" d:"<<d<<endl;
2    p++;
3    E[p] = u;
4    depth[p] = dep;
5    R[u] = p ;
6    dis[u] = d;

1    int siz = edge[u].size();
2    for ( int i = 0 ; i < siz ; i++)
3    {
4	int v = edge[u][i].fst;
5	if (v==pre) continue;
6	dfs(v,dep+1,d+edge[u][i].sec,u);

1	p++;
2	E[p] = u;
3	depth[p] = dep;
4    }
5}

1int _min( int l,int r)
2{
3    if (depth[l]<depth[r]) return l;
4    return r;
5}
6void rmq_init()
7{
8    for ( int i = 1 ; i <= 2*n+2 ; i++) dp[i][0] = i;

1    for ( int j = 1 ; (1<<j) <= 2*n+2 ; j++)
2	for ( int i = 1 ; i + (1<<j)-1 <= 2*n+2 ; i++)
3	dp[i][j] = _min(dp[i][j-1],dp[i+(1<<(j-1))][j-1]);
4}

 1int rmq_min( int l,int r)
 2{
 3    if (l>r) swap(l,r);
 4    int k = 0 ;
 5    while (1<<(k+1)<=r-l+1) k++;
 6    return _min(dp[l][k],dp[r-(1<<k)+1][k]);
 7}
 8int solve (int x,int y)
 9{
10    int LCA = E[rmq_min(R[x],R[y])];
11    int res = dis[x] + dis[y] - 2 * dis[LCA];
12    return res;
13}
14int main()
15{
16    #ifndef  ONLINE_JUDGE 
17	freopen("code/in.txt","r",stdin);
18  #endif

 1	ms(in,0);
 2	bool ok = false;
 3	while (~scanf("%d",&n)){
 4	    if (ok) puts("");
 5	    ok = true;
 6	    for ( int i = 0 ; i <= n ; i++) edge[i].clear();
 7	    for ( int i = 1 ; i <= n-1 ; i++)
 8	    {
 9		int u,v,w;
10		scanf("%d%d%d",&u,&v,&w);
11		edge[u].push_back(make_pair(v,w));
12		edge[v].push_back(make_pair(u,w));
13	    }

1	    p = 0 ;
2	    dfs(0,0,0,-1);
3	    rmq_init();

1	    scanf("%d",&q);
2	    while (q--)
3	    {
4		int x,y,z;
5		scanf("%d%d%d",&x,&y,&z);
6		int ans = solve(x,y)+solve(x,z)+solve(y,z);
7		printf("%d\n",ans/2);
8	    }
9	}

1#ifndef ONLINE_JUDGE  
2	fclose(stdin);
3#endif
4    return 0;
5}