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
| #include <bits/stdc++.h>
#define LL long long
#define PII pair<LL, LL>
using namespace std;
template <class T>
inline void read(T &res)
{
res = 0;
bool flag = 0;
char c = getchar();
while (c < '0' || '9' < c) { if (c == '-') flag = 1; c = getchar(); }
while ('0' <= c && c <= '9') res = (res << 3) + (res << 1) + (c ^ 48), c = getchar();
if (flag) res = -res;
}
template <class T, class... ARC>
inline void read(T &res, ARC &...com) { read(res), read(com...); }
template <class T>
void write(T res)
{
if (res < 0) putchar('-'), res = -res;
if (res > 9) write(res / 10);
putchar(res % 10 + '0');
}
template <>
inline void write(char c) { putchar(c); }
template <>
inline void write(char *s) { while (*s) putchar(*s++); }
template <class T, class... ARC>
inline void write(T res, ARC... com) { write(res), write(com...); }
const int N = 1005, M = 1e6 + 5;
int n, m, T;
struct Node{
int l, r;
vector<int> s;
}tr[M << 2];
struct Edge{
int o, u, val;
}e[M];
int fa[N], sz[N];
inline int find(int x)
{
if(fa[x] == x) return x;
int o = find(fa[x]);
sz[x] ^= sz[fa[x]];
return fa[x] = o;
}
inline bool cmp(int x, int y)
{
return e[x].val < e[y].val;
}
inline void merge(int u, int v)
{
if (find(u) == find(v)) return;
if (u > v) swap(u, v);
sz[fa[u]] ^= sz[u] ^ sz[v] ^ 1, fa[fa[u]] = fa[v];
}
inline void build(int x, int l, int r)
{
tr[x].l = l, tr[x].r = r;
vector<int> s;
for(int i = l;i <= r;i ++) s.emplace_back(i);
sort(s.begin(), s.end(), cmp);
for(int i = l;i <= r;i ++) fa[e[i].o] = e[i].o, fa[e[i].u] = e[i].u, sz[e[i].o] = 0, sz[e[i].u] = 0;
int flag = 0;
for(int i = s.size() - 1, o, u;i >= 0;i --)
{
o = e[s[i]].o, u = e[s[i]].u;
if(find(o) == find(u))
{
if(flag || (sz[o] + sz[u] + 1) % 2 == 0) continue;
tr[x].s.emplace_back(s[i]);
flag = 1;
break;
}
tr[x].s.emplace_back(s[i]);
merge(o, u);
}
if(l == r) return ;
int mid = l + r >> 1;
build(x << 1, l, mid);
build(x << 1 | 1, mid + 1, r);
}
inline vector<int> merge(vector<int> x, vector<int> y)
{
vector<int> s, res;
if(x.size() < y.size()) swap(x, y);
for(int i : y) x.emplace_back(i);
swap(s, x);
sort(s.begin(), s.end(), cmp);
for(int i : s) fa[e[i].o] = e[i].o, sz[e[i].o] = 0, fa[e[i].u] = e[i].u, sz[e[i].u] = 0;
for(int i = s.size() - 1, flag = 0, l, r;i >= 0;i --)
{
l = e[s[i]].o, r = e[s[i]].u;
if(find(l) == find(r))
{
if(flag || (sz[l] + sz[r] + 1) % 2 == 0) continue;
res.emplace_back(s[i]);
flag = 1;
break;
}
res.emplace_back(s[i]);
merge(l, r);
}
return res;
}
inline vector<int> query(int x, int l, int r)
{
if(l <= tr[x].l && tr[x].r <= r) return tr[x].s;
int mid = tr[x].l + tr[x].r >> 1;
vector<int> res;
if(l <= mid) res = merge(res, query(x << 1, l, r));
if(r > mid) res = merge(res, query(x << 1 | 1, l, r));
return res;
}
inline void work()
{
int l, r;
read(l, r);
vector<int> u = query(1, l, r);
for(int i = 1;i <= n;i ++) fa[i] = i, sz[i] = 0;
sort(u.begin(), u.end(), cmp);
for(int i = u.size() - 1, l, r;i >= 0;i --)
{
l = e[u[i]].o, r = e[u[i]].u;
if(find(l) == find(r) && (sz[l] + sz[r] + 1) % 2 != 0) return write(e[u[i]].val, '\n'), void();
merge(l, r);
}
puts("-1");
}
int main()
{
read(n, m, T);
for(int i = 1;i <= m;i ++) read(e[i].o, e[i].u, e[i].val);
build(1, 1, m);
while(T --) work();
return 0;
}
|