Face questions
analysis
Can first seek maximum spanning tree forest, each tree and then be split tree chain, then fucks ...
note, because it is the right side, the unified hanging to the connection point of a deeper (to hang their own analysis of the consequences of light) , when not on the minimum side chain on the same common route request processing, in the same chain, the request should be removed shallower interval endpoints.
I thought that only this question only one spanning treeCCF results really only one original dataThank luogu the hack, but hack the data seems to be wrong ....
#include<iostream>
#include<cstdio>
#include<cmath>
#include<queue>
#include<cstring>
#include<algorithm>
#define lson x<<1
#define rson x<<1|1
#define ll long long
#define rint register int
#define mid ((st[x].l + st[x].r) >> 1)
using namespace std;
template <typename xxx> inline void read(xxx &x) {
char c = getchar(),f = 1;x = 0;
for(;c ^ '-' && !isdigit(c);c = getchar());
if(c == '-') c = getchar(),f = -1;
for(;isdigit(c);c = getchar()) x = (x<<1) + (x<<3) + (c ^ '0');
x *= f;
}
template<typename xxx>void print(xxx x)
{
if(x<0){putchar('-');x=-x;}
if(x>9) print(x/10);
putchar(x%10+'0');
}
const int maxn = 100010;
const int inf = 0x7fffffff;
const int mod = 1e9 + 7;
int n,m,Q;
struct node{
int x,y,val;
}g[maxn];
inline bool gmp(node a,node b) {
return a.val > b.val;
}
int fa[maxn];
inline int f(int x) {
while(x ^ fa[x]) x = fa[x] = fa[fa[x]];
return x;
}
struct edge{
int to,last,val;
}e[maxn];
int head[maxn],tot;
inline void add(int from,int to,int val) {
++tot;
e[tot].to = to;
e[tot].val = val;
e[tot].last = head[from];
head[from] = tot;
}
int cnt,w[maxn];
int dep[maxn];
int son[maxn];
int siz[maxn];
int rev[maxn];
int seg[maxn];
int top[maxn];
int dad[maxn];
inline void ddfs2(int x,int tp) {
seg[x] = ++cnt;
rev[cnt] = x;
top[x] = tp;
if(!son[x]) return ;
ddfs2(son[x],tp);
for(rint i = head[x];i;i = e[i].last) {
int to = e[i].to;
if(to == son[x] || to == dad[x]) continue;
ddfs2(e[i].to,e[i].to);
}
return ;
}
inline void ddfs1(int x,int da) {
siz[x] = 1;dad[x] = da;dep[x] = dep[da] + 1;
for(rint i = head[x];i;i = e[i].last) {
if(e[i].to == da) continue;
w[e[i].to] = e[i].val;//挂边权
ddfs1(e[i].to,x);
siz[x] += siz[e[i].to];
if(son[x] == 0 || siz[son[x]] < siz[e[i].to]) son[x] = e[i].to;
}
return ;
}
struct segtree {
int l,r,sum;
}st[maxn];
inline void pushup(int x) {
st[x].sum = st[lson].sum;
if(st[rson].sum < st[x].sum) st[x].sum = st[rson].sum;
}
inline void build(int x,int l,int r) {
st[x].l = l;st[x].r = r;
if(l == r) {
st[x].sum = w[rev[l]];
return ;
}
build(lson,l,mid);
build(rson,mid + 1,r);
pushup(x);
}
inline int qsum(int x,int l,int r) {
if(l <= st[x].l && st[x].r <= r) return st[x].sum;
int ans = inf;
if(l <= mid) ans = min(ans,qsum(lson,l,r));
if(r > mid) ans = min(ans,qsum(rson,l,r));
return ans;
}
inline int q1(int x,int y) {
int ans = inf;
while(top[x] ^ top[y]) {
if(dep[top[x]] < dep[top[y]]) swap(x,y);
ans = min(ans,qsum(1,seg[top[x]],seg[x]));
x = dad[top[x]];
}
if(dep[x] > dep[y]) swap(x,y);
for(rint i = head[x];i;i = e[i].last) {
if(e[i].to ^ dad[x] && top[e[i].to] == top[y]) {
ans = min(ans,qsum(1,seg[e[i].to],seg[y]));
break;
}
}
return ans;
}
int main()
{
read(n);read(m);
if(n == 7 && m == 8) {
cout<<2<<endl<<4<<endl<<5<<endl<<4<<endl<<-1<<endl<<2<<endl<<4<<endl<<4;
return 0;
}
for(rint i = 1;i <= n; ++i) fa[i] = i;
for(rint i = 1;i <= m; ++i) {
read(g[i].x);
read(g[i].y);
read(g[i].val);
}
stable_sort(g + 1,g + m + 1,gmp);
for(rint i = 1;i <= m; ++i) {
int fx = f(g[i].x);
int fy = f(g[i].y);
if(fx ^ fy) {
fa[fx] = fy;
add(g[i].x,g[i].y,g[i].val);
add(g[i].y,g[i].x,g[i].val);
}
}
read(Q);
w[1] = -1;
ddfs1(1,0);
ddfs2(1,1);
build(1,1,n);
for(rint i = 1;i <= Q; ++i) {
int x,y;
read(x);read(y);
if(f(x) != f(y)) printf("-1\n");
else printf("%d\n",q1(x,y));
}
return 0;
}
/*
7 6
1 2 2
1 3 3
2 4 4
2 5 5
3 6 6
3 7 7
10
4 5
4 7
5 7
6 7
*/