Luogu P3313 [SDOI2014]旅行

题目链接 \(Click\) \(Here\)

假的主席树。。。实际上就是树链剖分维护十万棵动态开点的线段树，写起来和主席树比较相似。

真的是不能思维僵化啊，写题的时候一定要保证思考方向灵活\(+\)正确。

#include <bits/stdc++.h>
using namespace std;

const int N = 100010;

int tot, rt[N];

struct Segment_Node {
	int ls, rs, sum, max;
	
	void Init () {
		ls = rs = sum = max = 0;
	}
	
}t[N << 5];

#define mid ((l + r) >> 1)

void push_up (int p) {
	t[p].sum = t[t[p].ls].sum + t[t[p].rs].sum;
	t[p].max = max (t[t[p].ls].max, t[t[p].rs].max);
}

void modify (int &rt, int l, int r, int pos, int val) {
    if (rt == 0) rt = ++tot, t[rt].Init ();
	//printf ("rt = %d, l = %d, r = %d, pos = %d, val = %d\n", rt, l, r, pos, val);
	if (l != r) {
		if (pos <= mid) {
			modify (t[rt].ls, l, mid, pos, val);
		} else {
			modify (t[rt].rs, mid + 1, r, pos, val);
		}
		push_up (rt);
	} else {
		t[rt].sum = t[rt].max = val;
	}
	//printf ("t[%d].sum = %d, t[%d].max = %d\n", rt, t[rt].sum, rt, t[rt].max);
}

int query_sum (int l, int r, int nl, int nr, int p) {
	if (p == 0) return 0;
	if (nl <= l && r <= nr) {
		return t[p].sum;
	}
	int res = 0;
	if (nl <= mid) res += query_sum (l, mid, nl, nr, t[p].ls);
	if (mid < nr) res += query_sum (mid + 1, r, nl, nr, t[p].rs);
	return res;
}

int query_max (int l, int r, int nl, int nr, int p) {
	if (p == 0) return 0;
	if (nl <= l && r <= nr) {
		return t[p].max;
	}
	int res = 0;
	if (nl <= mid) res = max (res, query_max (l, mid, nl, nr, t[p].ls));
	if (mid < nr) res = max (res, query_max (mid + 1, r, nl, nr, t[p].rs));
	return res;
}

int cnt, head[N];

struct edge {
	int nxt, to;
}e[N << 1];

void add_len (int u, int v) {
	e[++cnt] = (edge) {head[u], v}, head[u] = cnt;
	e[++cnt] = (edge) {head[v], u}, head[v] = cnt;
}

int sz[N], pre[N], son[N], deep[N];

void dfs1 (int u, int fa) {
	sz[u] = 1;
	pre[u] = fa;
	deep[u] = deep[fa] + 1;
	int max_sz = 0;
	for (int i = head[u]; i; i = e[i].nxt) {
		int v = e[i].to;
		if (v != fa) {
			dfs1 (v, u);
			sz[u] += sz[v];
			if (sz[v] > max_sz) {
				son[u] = v;
				max_sz = sz[v];
			}
		}
	}
}

int n, m, rel[N], val[N];

int dfn[N], top[N], nodw[N];

void dfs2 (int u, int tp) {
	top[u] = tp;
	dfn[u] = ++dfn[0];
	//printf ("dfn[%d] = %d\n", u, dfn[0]);
	nodw[dfn[u]] = val[u];
	if (!son[u]) return;
	dfs2 (son[u], tp);
	for (int i = head[u]; i; i = e[i].nxt) {
		int v = e[i].to;
		if (v != pre[u] && v != son[u]) {
			dfs2 (v, v);
		}
	}
}

int get_sum (int u, int v, int _rel) {
	int res = 0;
	while (top[u] != top[v]) {
		//printf ("u = %d, v = %d, top[u] = %d, top[v] = %d, rel = %d\n", u, v, top[u], top[v], _rel);
		if (deep[top[u]] > deep[top[v]]) {
			//printf ("query_sum (%d, %d, %d, %d, %d) = %d\n", 1, n, dfn[top[u]], dfn[u], rt[_rel], query_sum (1, n, dfn[top[u]], dfn[u], rt[_rel]));
			res += query_sum (1, n, dfn[top[u]], dfn[u], rt[_rel]), u = pre[top[u]];
		} else {
			//printf ("query_sum (%d, %d, %d, %d, %d) = %d\n", 1, n, dfn[top[v]], dfn[v], rt[_rel], query_sum (1, n, dfn[top[v]], dfn[v], rt[_rel]));
			res += query_sum (1, n, dfn[top[v]], dfn[v], rt[_rel]), v = pre[top[v]];
		}
	}
	if (deep[u] > deep[v]) swap (u, v);
	res += query_sum (1, n, dfn[u], dfn[v], rt[_rel]);
	//printf ("u = %d, v = %d, top[u] = %d, top[v] = %d, rel = %d\n", u, v, top[u], top[v], _rel);
	//printf ("query_sum (%d, %d, %d, %d, %d) = %d\n", 1, n, dfn[u], dfn[v], rt[_rel], query_sum (1, n, dfn[u], dfn[v], rt[_rel]));
	return res;
}


int get_max (int u, int v, int _rel) {
	int res = 0;
	while (top[u] != top[v]) {
		if (deep[top[u]] > deep[top[v]]) {
			res = max (res, query_max (1, n, dfn[top[u]], dfn[u], rt[_rel])), u = pre[top[u]];
		} else {
			res = max (res, query_max (1, n, dfn[top[v]], dfn[v], rt[_rel])), v = pre[top[v]];
		}
	}
	if (deep[u] > deep[v]) swap (u, v);
	res = max (res, query_max (1, n, dfn[u], dfn[v], rt[_rel]));
	return res;
}

int main () {
	t[0].Init ();
	cin >> n >> m;
	for (int i = 1; i <= n; ++i) {
		cin >> val[i] >> rel[i];
    }
	for (int i = 1; i <= n - 1; ++i) {
		static int u, v;
		cin >> u >> v;
		add_len (u, v);
	}
	dfs1 (1, 0);
	dfs2 (1, 1);
	for (int u = 1; u <= n; ++u) {
		//printf ("u = %d, dfn[u] = %d, sz[u] = %d, top[u] = %d, son[u] = %d, deep[u] = %d\n", u, dfn[u], sz[u], top[u], son[u], deep[u]);
		//printf ("u = %d, rel[u] = %d, rt[rel[u]] = %d\n", u, rel[u], rt[rel[u]]);
		modify (rt[rel[u]], 1, n, dfn[u], val[u]);
		//printf ("rt[rel[u]] = %d\n", rt[rel[u]]);
	}
    for (int i = 1; i <= m; ++i) {
		static char opt[2];
		static int x, y;
		cin >> opt >> x >> y;
		if (opt[1] == 'C') { //点x宗教改为y
			modify (rt[rel[x]], 1, n, dfn[x], 0);
			rel[x] = y;
			modify (rt[rel[x]], 1, n, dfn[x], val[x]);
		}
		if (opt[1] == 'W') { //权值改为y
			val[x] = y;
			modify (rt[rel[x]], 1, n, dfn[x], val[x]);
		}
		if (opt[1] == 'S') {
			cout << get_sum (x, y, rel[y]) << endl;;
		}
		if (opt[1] == 'M') {
			cout << get_max (x, y, rel[y]) << endl;
		}
	}
}