【BZOJ1095】[ZJOI2007]Hide 捉迷藏【动态树分治】

【题目链接】

学习了一发可删堆。

找重心那里忘了写!del[g[i].v]，RE无数发。

/* Pigonometry */
#include 
#include 
#include 
#include 

using namespace std;

const int maxn = 100005, maxm = maxn << 1, maxk = 21, inf = 0x3f3f3f3f;

int n, head[maxn], cnt;

int root, clo, tot, bin[maxk], lg[maxm];
int size[maxn], depth[maxn], sm[maxn], pre[maxn], st[maxk][maxm], dfn[maxn], del[maxn], col[maxn];

struct _heap {
	priority_queue A, B;

	void update() {
		for(; B.size() && A.top() == B.top(); A.pop(), B.pop());
	}

	void push(int x) {
		A.push(x);
	}

	void pop() {
		update();
		A.pop();
	}

	void erase(int x) {
		B.push(x);
	}

	int size() {
		return A.size() - B.size();
	}

	int first() {
		update();
		return A.size() ? A.top() : 0;
	}

	int second() {
		if(size() < 2) return 0;
		int x = first(); pop();
		int y = first(); push(x);
		return y;
	}
} A, B[maxn], C[maxn];

struct _edge {
	int v, next;
} g[maxn << 1];

inline int iread() {
	int f = 1, x = 0; char ch = getchar();
	for(; ch < '0' || ch > '9'; ch = getchar()) f = ch == '-' ? -1 : 1;
	for(; ch >= '0' && ch <= '9'; ch = getchar()) x = x * 10 + ch - '0';
	return f * x;
}

inline void add(int u, int v) {
	g[cnt] = (_edge){v, head[u]};
	head[u] = cnt++;
}

inline void dfs(int x, int f) {
	st[0][++clo] = depth[x];
	dfn[x] = clo;
	for(int i = head[x]; ~i; i = g[i].next) if(g[i].v ^ f) {
		depth[g[i].v] = depth[x] + 1;
		dfs(g[i].v, x);
		st[0][++clo] = depth[x];
	}
}

inline int getlca(int u, int v) {
	u = dfn[u]; v = dfn[v];
	if(u > v) swap(u, v);
	int t = lg[v - u + 1];
	return min(st[t][u], st[t][v - bin[t] + 1]);
}
	
inline int dis(int u, int v) {
	return depth[u] + depth[v] - (getlca(u, v) << 1);
}

inline void find(int x, int f) {
	size[x] = 1; sm[x] = 0;
	for(int i = head[x]; ~i; i = g[i].next) if(g[i].v ^ f && !del[g[i].v]) {
		find(g[i].v, x);
		size[x] += size[g[i].v];
		sm[x] = max(sm[x], size[g[i].v]);	
	}
	sm[x] = max(sm[x], tot - size[x]);	
	if(sm[x] < sm[root]) root = x;
}

inline void divide(int x, int f) {
	pre[x] = f; del[x] = 1;
	for(int i = head[x]; ~i; i = g[i].next) if(g[i].v ^ f && !del[g[i].v]) {
		root = 0; tot = size[g[i].v];
		find(g[i].v, x); divide(root, x);
	}
}

inline void turnoff(int x, int f) {
	if(x == f) {
		B[x].push(0);
		if(B[x].size() == 2) A.push(B[x].first());
	}
	if(!pre[f]) return;

	int p = pre[f], d = dis(x, p), tmp = C[f].first();
	C[f].push(d);

	if(d > tmp) {
		int mx = B[p].first() + B[p].second(), sz = B[p].size();
		B[p].push(d);
		if(tmp) B[p].erase(tmp);
		int now = B[p].first() + B[p].second();
		if(now > mx) {
			if(sz >= 2) A.erase(mx);
			if(B[p].size() >= 2) A.push(now);
		}
	}
	turnoff(x, p);
}

inline void turnon(int x, int f) {
	if(x == f) {
		if(B[x].size() == 2) A.erase(B[x].first());
		B[x].erase(0);
	}
	if(!pre[f]) return;

	int p = pre[f], d = dis(x, p), tmp = C[f].first();
	C[f].erase(d);

	if(d == tmp) {
		int mx = B[p].first() + B[p].second(), sz = B[p].size();
		B[p].erase(d);
		if(C[f].first()) B[p].push(C[f].first());
		int now = B[p].first() + B[p].second();
		if(now < mx) {
			if(sz >= 2) A.erase(mx);
			if(B[p].size() >= 2) A.push(now);
		}
	}
	turnon(x, p);
}

int main() {
	n = iread();
	for(int i = 0; i <= n; i++) head[i] = -1; cnt = 0;

	bin[0] = 1;
	for(int i = 1; i < maxk; i++) bin[i] = bin[i - 1] << 1;
	lg[0] = -1;
	for(int i = 1; i < maxm; i++) lg[i] = lg[i >> 1] + 1;


	for(int i = 1; i < n; i++) {
		int u = iread(), v = iread();
		add(u, v); add(v, u);
	}

	dfs(1, 0);
	for(int j = 1; j < maxk; j++) for(int i = 1; i <= clo; i++) if(i + bin[j] - 1 <= clo)
		st[j][i] = min(st[j - 1][i], st[j - 1][i + bin[j - 1]]);

	sm[0] = inf; root = 0; tot = n;
	find(1, 0); divide(root, 0);

	for(int i = 1; i <= n; i++) C[i].push(0), col[i] = 1;
	for(int i = 1; i <= n; i++) turnoff(i, i);

	int node = n;
	for(int T = iread(); T; T--) {
		char ch = getchar(); for(; ch != 'C' && ch != 'G'; ch = getchar());
		if(ch == 'G') {
			if(node <= 1) printf("%d\n", node - 1);
			else printf("%d\n", A.first());
		}
		else if(ch == 'C') {
			int u = iread();
			if(col[u] == 1) node--, turnon(u, u);
			else node++, turnoff(u, u);
			col[u] ^= 1;
		}
	}
	return 0;
}