1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
| #include<bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
const int maxn = 100005;
const ull seed = 1000000007;
ull H[maxn], H2[maxn];
ull size[maxn];
vector<int> G1[maxn], G2[maxn];
map<ull, bool> mp;
int N, R;
int ans = maxn;
void dfs1(int u, int fa) {
H[u] = size[u] = 1;
for (vector<int>::iterator it = G1[u].begin(); it != G1[u].end(); it++) {
int v = *it;
if (v == fa) continue;
dfs1(v, u);
size[u] += size[v];
H[u] ^= (H[v] * seed + size[v]);
}
}
void dfs2(int u, int fa) {
if (u != R) {
H2[u] = H[u] ^ ((H2[fa] ^ (H[u] * seed + size[u])) * seed + ((ull)N - size[u]));
} else H2[u] = H[u];
for (vector<int>::iterator it = G1[u].begin(); it != G1[u].end(); it++) {
int v = *it;
if (v == fa) continue;
dfs2(v, u);
}
}
void dfs3(int u, int fa) {
H[u] = size[u] = 1;
for (vector<int>::iterator it = G2[u].begin(); it != G2[u].end(); it++) {
int v = *it;
if (v == fa) continue;
dfs3(v, u);
size[u] += size[v];
H[u] ^= (H[v] * seed + size[v]);
}
}
void dfs4(int u, int fa) {
if (u != R) {
H2[u] = H[u] ^ ((H2[fa] ^ (H[u] * seed + size[u])) * seed + ((ull)N + 1 - size[u]));
} else H2[u] = H[u];
for (vector<int>::iterator it = G2[u].begin(); it != G2[u].end(); it++) {
int v = *it;
if (v == fa) continue;
dfs4(v, u);
}
}
int main() {
scanf("%d", &N);
for (register int i = 1; i < N; ++i) {
int u, v;
scanf("%d%d", &u, &v);
G1[u].push_back(v);
G1[v].push_back(u);
}
R = 1;
dfs1(1, 0);
dfs2(1, 0);
for (register int i = 1; i <= N; ++i) {
int u, v;
scanf("%d%d", &u, &v);
G2[u].push_back(v);
G2[v].push_back(u);
}
for (register int i = 1; i <= N; ++i)
mp[H2[i]] = 1;
R = 2;
dfs3(2, 0);
dfs4(2, 0);
for (register int i = 1; i <= 1; ++i) {
if ((int)G2[i].size() == 1) {
ull w = H2[G2[i][0]] ^ (H[i] * seed + 1);
if (mp[w]) return printf("%d", i), 0;
}
}
R = 1;
dfs3(1, 0);
dfs4(1, 0);
for (register int i = 2; i <= N + 1; ++i) {
if ((int)G2[i].size() == 1) {
ull w = H2[G2[i][0]] ^ (H[i] * seed + 1);
if (mp[w]) return printf("%d", i), 0;
}
}
return 0;
}
|