bzoj3669

一维排序 另一维lct维护最小生成树

#include <cstdio>
#include <iostream>
#include <algorithm>
using namespace std;

int ch[150010][2],rv[150010],fa[150010],st[150010],tp;
int ma[150010],x[150010],nu[150010],mn[150010];

int n,m;
int head[50010];
int ans = 0x3f3f3f3f;
struct edge {
	int u,v,a,b;
	bool operator < (const edge &b)const {
		return a < b.a;
	}
}e[100010];

int read_int () {
	char c = getchar();
	int re = 0;
	for(;c > '9' || c < '0';c = getchar());
	for(;c >= '0' && c <= '9';c = getchar())
		re = re * 10 + c - '0';
	return re;
}

int find (int u) {
	if(head[u] == u)
		return u;
	return head[u] = find(head[u]);
}

void pu (int u) {
	ma[u] = x[u];
	mn[u] = nu[u];
	if(ma[u] < ma[ch[u][0]]) {
		ma[u] = ma[ch[u][0]];
		mn[u] = mn[ch[u][0]];
	}
	if(ma[u] < ma[ch[u][1]]) {
		ma[u] = ma[ch[u][1]];
		mn[u] = mn[ch[u][1]];
	}
}

void reverse (int u) {
	int t = ch[u][0];
	ch[u][0] = ch[u][1];
	ch[u][1] = t;
	rv[u] ^= 1;
}

void pd (int u) {
	if(!rv[u])
		return;
	rv[u] = 0;
	reverse(ch[u][0]);
	reverse(ch[u][1]);
}

void rot (int u,int d) {
	ch[fa[u]][d ^ 1] = ch[u][d];
	if(ch[u][d])
		fa[ch[u][d]] = fa[u];
	int t = fa[fa[u]];
	fa[fa[u]] = u;
	ch[u][d] = fa[u];
	fa[u] = t;
	
	pu(ch[u][d]);
	pu(u);
	
	if(!t)
		return;
	if(ch[t][0] == ch[u][d])
		ch[t][0] = u;
	if(ch[t][1] == ch[u][d])
		ch[t][1] = u;
}

void splay (int u) {
	st[tp = 1] = u;
	int t = u;
	while(ch[fa[t]][0] == t || ch[fa[t]][1] == t) {
		t = fa[t];
		st[++tp] = t;
	}
	while(tp)
		pd(st[tp--]);
		
	while(ch[fa[u]][0] == u || ch[fa[u]][1] == u) {
		if(ch[fa[fa[u]]][0] != fa[u] && ch[fa[fa[u]]][1] != fa[u]) {
			if(ch[fa[u]][0] == u)
				rot(u,1);
			else rot(u,0);
		}
		else {
			int d = ch[fa[fa[u]]][0] == fa[u];
			if(ch[fa[u]][d] == u) {
				rot(u,d ^ 1);
				rot(u,d);
			}
			else {
				rot(u,d);
				rot(u,d);
			}
		}
	}
}

void access (int u) {
	int v = 0;
	while(u) {
		splay(u);
		ch[u][1] = v;
		pu(u);
		v = u;
		u = fa[u];
	}
}

void mtr (int u) {
	access(u);
	splay(u);
	reverse(u);
}

void link (int u,int v) {
	mtr(u);
	mtr(v);
	fa[v] = u;
}

void cut (int u,int v) {
	mtr(u);
	access(u);
	splay(v);
	fa[v] = 0;
}

int main () {
	n = read_int();
	m = read_int();
	
	for(int i = 1;i <= n;++i)
		head[i] = i;
	
	for(int i = 1;i <= m;++i) {
		e[i].u = read_int();
		e[i].v = read_int();
		e[i].a = read_int();
		e[i].b = read_int();
	}
	
	sort(e + 1,e + 1 + m);
	
	e[0].a = e[1].a;
	for(int i = 1;i <= m + 1;++i) {
		if(e[i].a != e[i - 1].a && find(1) == find(n)) {
			mtr(1);
			access(n);
			splay(1);
			ans = min(ans,e[i - 1].a + ma[1]);
		}
		if(i == m + 1)
			break;
		if(e[i].u == e[i].v)
			continue;
		if(find(e[i].u) == find(e[i].v)) {
			mtr(e[i].u);
			access(e[i].v);
			splay(e[i].u);
			if(ma[e[i].u] < e[i].b)
				continue;
			int t = mn[e[i].u];
			cut(t + n,e[t].v);
			cut(t + n,e[t].u);
		}
		else head[find(e[i].u)] = find(e[i].v);
		x[i + n] = ma[i + n] = e[i].b;
		nu[i + n] = mn[i + n] = i;
		link(i + n,e[i].u);
		link(i + n,e[i].v);
	}
	if(ans == 0x3f3f3f3f)
		ans = -1;
	printf("%d\n",ans);
	return 0;
}