【BZOJ 3735】苹果树 树上莫队(树分块+离线莫队+鬼畜的压行)

#include<cmath>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define N 50003
#define M 100003
#define read(x) x=getint()
using namespace std;
inline int getint() {int k = 0, fh = 1; char c = getchar();	for(; c < ‘0‘ || c > ‘9‘; c = getchar()) if (c == ‘-‘) fh = -1; for(; c >= ‘0‘ && c <= ‘9‘; c = getchar()) k = k * 10 + c - ‘0‘; return k * fh;}
int n, m, color[N], cnt = 0, fa[N][16], deep[N], dfn[N << 1], now = 0;
int belong[N], cntblo = 0, sqrblo, top = 0, sta[N], ans[M], colsum[N], point[N];
short v[N];
struct Enode {int nxt, to;} E[N << 1];
struct node {int x, y, a, b, id;} q[M];
inline bool cmp(node A, node B) {return belong[A.x] == belong[B.x] ? dfn[A.y] < dfn[B.y] : dfn[A.x] < dfn[B.x];}
inline void ins(int x, int y) {E[++cnt].nxt = point[x]; E[cnt].to = y; point[x] = cnt;}

inline void dfs(int x) {
	dfn[x] = ++cnt;
	int mark = top;
	for(int i = 1; i <= 15; ++i)
		fa[x][i] = fa[fa[x][i - 1]][i - 1];
	for(int tmp = point[x]; tmp; tmp = E[tmp].nxt) {
		int v = E[tmp].to;
		if (v == fa[x][0]) continue;
		deep[v] =deep[x] + 1;
		fa[v][0] = x;
		dfs(v);
		if (top - mark >= sqrblo) {
			++cntblo;
			while (top != mark)
				belong[sta[top--]] = cntblo;
		}
	}
	sta[++top] = x; 
}

inline int LCA(int x, int y) {
	if (deep[x] < deep[y])
		swap(x, y);
	int k = deep[x] - deep[y];
	for(int j = 15; j >= 0; --j)
		if (k & (1 << j))
			x = fa[x][j];
	if (x == y) return x;
	for(int j = 15; j >= 0; --j)
		if (fa[x][j] != fa[y][j])
			x = fa[x][j], y = fa[y][j];
	return fa[x][0];
}

inline void pushup(int x) {
	if (v[x]) {
		--colsum[color[x]];
		if (!colsum[color[x]])
			--now;
	} else {
		if (!colsum[color[x]])
			++now;
		++colsum[color[x]];
	}
	v[x] ^= 1;
}

inline void change(int x, int y) {
	while (x != y) {
		if (deep[x] < deep[y])
			pushup(y), y = fa[y][0];
		else
			pushup(x), x = fa[x][0];
	} //O)Z这个方法好神啊！！！我为什么想不到一个一个往上跳呢QAQ 
}

int main() {
	read(n); read(m);
	for(int i = 1; i <= n; ++i)
		read(color[i]);
	int u, v;
	for(int i = 1; i <= n; ++i) {
		read(u); read(v);
		if (u == 0 || v == 0) continue;
		ins(u, v);
		ins(v, u);
	}
	sqrblo = ceil(sqrt(n));
	cnt = 0;
	dfs(1);
	while (top)
		belong[sta[top--]] = cntblo;
	
	for(int i = 1; i <= m; ++i) {
		read(q[i].x); read(q[i].y); read(q[i].a); read(q[i].b); q[i].id = i;
		if (dfn[q[i].x] > dfn[q[i].y])
			swap(q[i].x, q[i].y);
	}
	
	sort(q + 1, q + m + 1, cmp);
	q[0].x = q[0].y = 1;
	
	for(int i = 1; i <= m; ++i) {
		change(q[i - 1].x, q[i].x);
		change(q[i - 1].y, q[i].y);
		int lca = LCA(q[i].x, q[i].y);
		pushup(lca);
		ans[q[i].id] = now;
		if (colsum[q[i].a] && colsum[q[i].b] && q[i].a != q[i].b)
			--ans[q[i].id];
		pushup(lca);
	}
	
	for(int i = 1; i <= m; ++i)
		printf("%d\n", ans[i]);
	return 0;
}