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
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
#include <bits/stdc++.h>
namespace IO {
inline char read() {
static const int IN_LEN = 1000000;
static char buf[IN_LEN], *s, *t;
s == t ? t = (s = buf) + fread(buf, 1, IN_LEN, stdin) : 0;
return s == t ? -1 : *s++;
}
template <typename T>
inline void read(T &x) {
static char c;
static bool iosig;
for (c = read(), iosig = false; !isdigit(c); c = read()) {
if (c == -1) return;
c == '-' ? iosig = true : 0;
}
for (x = 0; isdigit(c); c = read()) x = (x + (x << 2) << 1) + (c ^ '0');
iosig ? x = -x : 0;
}
const int OUT_LEN = 1000000;
char obuf[OUT_LEN], *oh = obuf;
inline void print(char c) {
oh == obuf + OUT_LEN ? (fwrite(obuf, 1, OUT_LEN, stdout), oh = obuf) : 0;
*oh++ = c;
}
template <typename T>
inline void print(T x) {
static int buf[30], cnt;
if (x == 0) {
print('0');
} else {
x < 0 ? (print('-'), x = -x) : 0;
for (cnt = 0; x; x /= 10) buf[++cnt] = x % 10 | 48;
while (cnt) print((char)buf[cnt--]);
}
}
inline void flush() { fwrite(obuf, 1, oh - obuf, stdout); }
}
namespace Task {
const int MAXN = 101010;
const int INF = INT_MAX >> 1;
struct Node {
int v, w;
Node(int v, int w) : v(v), w(w) {}
};
std::vector<Node> edge[MAXN];
inline void addEdge(const int u, const int v, const int w) {
edge[u].push_back(Node(v, w));
edge[v].push_back(Node(u, w));
}
int sz[MAXN], n, limitL, limitR, L = -1, R, dep[MAXN], q[MAXN];
bool vis[MAXN];
typedef std::pair<int, int> Pair;
Pair ans;
inline void dfsSize(int u, int fa) {
sz[u] = 1;
for (register int i = 0, v; i < edge[u].size(); i++)
if (!vis[v = edge[u][i].v] && v != fa) dfsSize(v, u), sz[u] += sz[v];
}
inline int getCenter(int u, int fa, int n) {
register int s = n - sz[u];
for (register int i = 0, v; i < edge[u].size(); i++) {
if (!vis[v = edge[u][i].v] && v != fa) {
if (int ret = getCenter(v, u, n)) return ret;
s = std::max(s, sz[v]);
}
}
return (s << 1) <= n ? u : 0;
}
inline bool cmp(const Node &a, const Node &b) { return dep[a.v] < dep[b.v]; }
inline void getDep(int u, int fa) {
dep[u] = 1;
for (register int i = 0, v; i < edge[u].size(); i++) {
if (!vis[v = edge[u][i].v] && v != fa) {
getDep(v, u), dep[u] = std::max(dep[u], dep[v] + 1);
}
}
}
Pair a[MAXN], b[MAXN], tmp;
inline void dfs(int u, int fa, int d, int val, int limit) {
if (val > b[d].first) b[d] = std::make_pair(val, u);
for (register int i = 0, v; i < edge[u].size(); i++) {
if (!vis[v = edge[u][i].v] && v != fa)
dfs(v, u, d + 1, val + (edge[u][i].w >= limit ? 1 : -1), limit);
}
}
inline bool check(int u, int limit) {
for (register int i = 0; i < dep[u]; i++) a[i] = std::make_pair(-INF, 0);
a[0] = std::make_pair(0, u);
register int pp = 0;
for (register int i = 0, v; i < edge[u].size(); i++) {
if (!vis[v = edge[u][i].v]) {
for (register int j = 0; j <= dep[v]; j++)
b[j] = std::make_pair(-INF, 0);
dfs(v, u, 1, edge[u][i].w >= limit ? 1 : -1, limit);
register int l = 0, r = 0, end = pp;
for (register int j = 0; j <= dep[v]; j++) {
while (j + end >= limitL && end >= 0) {
while (l < r && a[q[r - 1]] <= a[end]) r--;
q[r++] = end--;
}
while (l < r && q[l] + j > limitR) l++;
if (l < r && a[q[l]].first + b[j].first >= 0)
return tmp = std::make_pair(a[q[l]].second, b[j].second),
true;
}
for (register int j = 0; j <= dep[v]; j++)
a[j] = std::max(a[j], b[j]);
pp = dep[v];
}
}
return false;
}
inline void calc(int u) {
getDep(u, 0);
std::sort(edge[u].begin(), edge[u].end(), cmp);
register int l = L, r = R;
if (!check(u, l)) return;
while (l + 1 != r) {
register int mid = l + r >> 1;
if (check(u, mid))
l = mid;
else
r = mid;
}
if (l > L) ans = tmp, L = l;
}
inline void solve(int u) {
dfsSize(u, 0);
vis[u = getCenter(u, 0, sz[u])] = true;
calc(u);
for (register int i = 0, v; i < edge[u].size(); i++)
if (!vis[v = edge[u][i].v]) solve(v);
}
inline void solve() {
using namespace IO;
read(n), read(limitL), read(limitR);
for (register int i = 1, u, v, w; i < n; i++)
read(u), read(v), read(w), addEdge(u, v, w), R = std::max(R, w + 1);
solve(1);
print(ans.first), print(' '), print(ans.second);
}
}
int main() {
Task::solve();
IO::flush();
return 0;
}
|
