UOJ#274. 【清华集训2016】温暖会指引我们前行

题面

UOJ

题解

\(LCT\)板子题

维护一个最大生成树即可

Code

#include<bits/stdc++.h>

#define LL long long
#define RG register

using namespace std;
template<class T> inline void read(T &x) {
	x = 0; RG char c = getchar(); bool f = 0;
	while (c != '-' && (c < '0' || c > '9')) c = getchar(); if (c == '-') c = getchar(), f = 1;
	while (c >= '0' && c <= '9') x = x*10+c-48, c = getchar();
	x = f ? -x : x;
	return ;
}
template<class T> inline void write(T x) {
	if (!x) {putchar(48);return ;}
	if (x < 0) x = -x, putchar('-');
	int len = -1, z[20]; while (x > 0) z[++len] = x%10, x /= 10;
	for (RG int i = len; i >= 0; i--) putchar(z[i]+48);return ;
}
const int N = 600010;
int n, m, v;
int Min[N], pos[N], ch[N][2], fa[N], S[N], top, val[N], len[N], w[N];
bool rev[N];
void pushup(int x) {
	Min[x] = val[x]; pos[x] = x;
	if (ch[x][0] && Min[ch[x][0]] < Min[x]) Min[x] = Min[ch[x][0]], pos[x] = pos[ch[x][0]];
	if (ch[x][1] && Min[ch[x][1]] < Min[x]) Min[x] = Min[ch[x][1]], pos[x] = pos[ch[x][1]];
	w[x] = w[ch[x][0]] + w[ch[x][1]] + len[x];
}
void putrev(int x) {
	swap(ch[x][0], ch[x][1]);
	rev[x] ^= 1;
}
void pushdown(int x) {
	if (rev[x]) {
		if (ch[x][0]) putrev(ch[x][0]);
		if (ch[x][1]) putrev(ch[x][1]);
		rev[x] = 0;
	}
}
bool isroot(int x) {
	return ch[fa[x]][0] != x && ch[fa[x]][1] != x;
}
#define get(x) (ch[fa[x]][1] == x)
void rotate(int x) {
	int y = fa[x], z = fa[y], k = get(x);
	if (!isroot(y)) ch[z][get(y)] = x;
	fa[x] = z;
	ch[y][k] = ch[x][k ^ 1]; fa[ch[x][k ^ 1]] = y;
	ch[x][k ^ 1] = y; fa[y] = x;
	pushup(y);
}
void splay(int x) {
	S[top = 1] = x;
	for (int i = x; !isroot(i); i = fa[i]) S[++top] = fa[i];
	for (int i = top; i; i--) pushdown(S[i]);
	while (!isroot(x)) {
		int y = fa[x];
		if (!isroot(y))
			(get(x) ^ get(y)) ? rotate(x) : rotate(y);
		rotate(x);
	}
	pushup(x);
}
void access(int x) { for (int y = 0; x; y = x, x = fa[x]) splay(x), ch[x][1] = y, pushup(x); }
void makeroot(int x) { access(x); splay(x); putrev(x); }
void link(int x, int y) { makeroot(x); fa[x] = y; }
void split(int x, int y) { makeroot(x); access(y); splay(y); }
void cut(int x, int y) { split(x, y); fa[x] = ch[y][0] = 0; pushup(y); }
char s[10];
int Fa[N], E[N][2];
int find(int x) {
	return x == Fa[x] ? x : Fa[x] = find(Fa[x]);
}
int main() {
	//freopen(".in", "r", stdin);
	//freopen(".out", "w", stdout);
	read(n), read(m);
	for (int i = 1; i <= n; i++) val[i] = 2147483647, Fa[i] = i; 
	while (m--) {
		scanf("%s", s);
		if (s[0] == 'f') {
			int id, u, v;
			read(id), read(u), read(v);
			id += n + 1; u++; v++;
			E[id][0] = u; E[id][1] = v;
			read(val[id]), read(len[id]);
			if (find(u) != find(v))
				link(u, id), link(id, v);			
			else {
				split(u, v);
				if (Min[v] < val[id]) {
					int k = pos[v];
					cut(E[k][0], k), cut(k, E[k][1]);
					link(u, id), link(id, v);
				}
			}
			Fa[find(v)] = find(u);
		}
		else if (s[0] == 'm') {
			int u, v;
			read(u), read(v);
			u++; v++;
			if (find(u) != find(v)) {
				puts("-1");
				continue;
			}
			split(u, v);
			printf("%d\n", w[v]);
		}
		else {
			int id, l;
			read(id), read(l);
			id += n + 1;
			len[id] = l;
			splay(id);
			pushup(id);
		}
	}
	return 0;
}