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| #include <bits/stdc++.h>
#define x first
#define y second
#define y1 Y1
#define y2 Y2
#define mp make_pair
#define pb push_back
using namespace std;
typedef long long LL;
typedef pair <int, int> pii;
inline void proc_status ()
{
ifstream t ("/proc/self/status");
cerr << string (istreambuf_iterator <char> (t), istreambuf_iterator <char> ()) <<endl;
}
template <typename T> inline int Chkmin (T &a, T b) {return a > b ? a = b, 1 : 0; }
template <typename T> inline int Chkmax (T &a, T b) {return a < b ? a = b, 1 : 0; }
inline int read ()
{
int sum = 0, fl = 1; char ch = getchar();
for (; !isdigit(ch); ch = getchar()) if (ch == '-') fl = -1;
for (; isdigit(ch); ch = getchar()) sum = (sum << 3) + (sum << 1) + ch - '0';
return sum * fl;
}
const int Maxn = 10000 + 10, Maxm = 50000, inf = 0x3f3f3f3f;
int N, M, Q;
struct edge
{
int x, y, z;
}E[Maxm];
inline int cmp (edge a, edge b) { return a.z > b.z; }
namespace DSU
{
int fa[Maxn];
inline void init () { for (int i = 1; i <= N; ++i) fa[i] = i; }
inline int find (int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); }
inline void link (int x, int y) { fa[find(y)] = find(x); }
}
int e, Begin[Maxn], To[Maxm << 1], Next[Maxm << 1], W[Maxm << 1];
inline void add_edge (int x, int y, int z) { To[++e] = y; Next[e] = Begin[x]; Begin[x] = e; W[e] = z; }
int anc[22][Maxn], dep[Maxn], Min[22][Maxn];
inline void dfs (int x)
{
dep[x] = dep[anc[0][x]] + 1;
for (int i = 1; i <= 20; ++i)
{
anc[i][x] = anc[i - 1][anc[i - 1][x]];
Min[i][x] = min(Min[i - 1][x], Min[i - 1][anc[i - 1][x]]);
}
for (int i = Begin[x]; i; i = Next[i])
{
int y = To[i];
if (y == anc[0][x]) continue ;
Min[0][y] = W[i];
anc[0][y] = x;
dfs(y);
}
}
inline int Get_ans (int x, int y)
{
int ans = inf;
if (dep[x] < dep[y]) swap(x, y);
for (int i = 20; i >= 0; --i)
if (dep[anc[i][x]] >= dep[y]) Chkmin(ans, Min[i][x]), x = anc[i][x];
if (x == y) return ans;
Chkmin (ans, min(Min[0][x], Min[0][y]));
for (int i = 20; i >= 0; --i)
if (anc[i][x] != anc[i][y]) Chkmin(ans, Min[i][x]), Chkmin(ans, Min[i][y]), x = anc[i][x], y = anc[i][y];
Chkmin (ans, min(Min[0][x], Min[0][y]));
return ans;
}
inline void Solve ()
{
sort (E + 1, E + M + 1, cmp);
DSU :: init();
for (int i = 1; i <= M; ++i)
{
int x = E[i].x, y = E[i].y, z = E[i].z;
if (DSU :: find(x) == DSU :: find(y)) continue;
add_edge (x, y, z);
add_edge (y, x, z);
DSU :: link (x, y);
}
for (int s = 1; s <= N; ++s)
if (!dep[s])
{
for (int i = 0; i <= 20; ++i) Min[i][s] = inf;
dfs(s);
}
Q = read();
while (Q--)
{
int x = read(), y = read();
if (DSU :: find(x) != DSU :: find(y)) printf("-1\n");
else printf("%d\n", Get_ans(x, y));
}
}
inline void Input ()
{
N = read(), M = read();
for (int i = 1; i <= M; ++i) E[i].x = read(), E[i].y = read(), E[i].z = read();
}
int main()
{
#ifndef ONLINE_JUDGE
freopen("truck.in", "r", stdin);
freopen("truck.out", "w", stdout);
#endif
Input();
Solve();
return 0;
}
|