http://blog.youkuaiyun.com/lyhypacm/article/details/6734748
dfs序是针对某条路径, 利用根到路径
#include <cstdio>
#include <cstring>
#include <iostream>
#include <queue>
#include <cstdlib>
#include <cmath>
#include <stack>
#include <map>
#include <vector>
#include <string>
#include <algorithm>
const double pi=cos(-1.);
const double eps=10e-6;
const double eps1=10e-9;
const int inf=0x7fffffff;
///const int inf=0x3f3f3f3f;
const long long infl=1ll<<62;
///******macro defination******///
#define cas(a) int a; scanf("%d", &a); while (a--)
#define cas1(x, a) int a; scanf("%d", &a); for (int x=1; x<=a; ++x)
#define int(a) int a; scanf("%d", &a)
#define char(a) char a; scanf("%c", &a)
#define strr(a, x) char a[x]; scanf("%s", &a)
#define clean(a, x) memset (a, x, sizeof(a));
#define copy(a, b) memcpy(a, b, sizeof(a));
#define up(x,a) for(int x=0; x<a; ++x)
#define down(x,a) for(int x=a-1; x>=0; --x)
#define up1(x,a) for (i