BZOJ 1984: 月下“毛景树” (树链剖分+线段树)

注意赋值和加法的标记下传优先级.具体看代码.

CODE

#include <vector>
#include <queue>
#include <cstdio>
#include <cctype>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long LL;
#define ls (i<<1)
#define rs (i<<1|1)
inline void read(int &num) {
	char ch; int flg=1; while(!isdigit(ch=getchar()))if(ch=='-')flg=-flg;
	for(num=0; isdigit(ch); num=num*10+ch-'0',ch=getchar()); num*=flg;
}
const int MAXN = 100005;
const int INF = 1e9;
int n, w[MAXN], dfn[MAXN], seq[MAXN], tmr;
int fir[MAXN], cnt, bel[MAXN]; //bel表示某条边下面是哪个点
struct edge { int to, nxt, w, i; }e[MAXN<<1];
inline void add(int u, int v, int wt, int id) {
	e[cnt] = (edge){ v, fir[u], wt, id }, fir[u] = cnt++;
	e[cnt] = (edge){ u, fir[v], wt, id }, fir[v] = cnt++;
}
int dep[MAXN], fa[MAXN], sz[MAXN], top[MAXN], son[MAXN];
void dfs(int u, int ff) {
	dep[u] = dep[fa[u]=ff] + (sz[u]=1);
	for(int v, i = fir[u]; ~i; i = e[i].nxt)
		if((v=e[i].to) != fa[u]) {
			w[bel[e[i].i] = v] = e[i].w, dfs(v, u), sz[u] += sz[v];
			if(sz[v] > sz[son[u]]) son[u] = v;
		}
}
void dfs2(int u, int tp) {
	top[u] = tp; seq[dfn[u] = ++tmr] = u;
	if(son[u]) dfs2(son[u], tp);
	for(int v, i = fir[u]; ~i; i = e[i].nxt)
		if((v=e[i].to) != son[u] && v != fa[u]) dfs2(v, v);
}
int mx[MAXN<<2], lz[MAXN<<2], c[MAXN<<2];
inline void upd(int i) { mx[i] = max(mx[ls], mx[rs]); }
inline void mt(int i) {
	if(~c[i]) { //先传赋值标记
		mx[ls] = mx[rs] = c[i];
		lz[ls] = lz[rs] = 0;
		c[ls] = c[rs] = c[i];
		c[i] = -1;
	}
	if(lz[i]) {
		mx[ls] += lz[i], mx[rs] += lz[i];
		lz[ls] += lz[i], lz[rs] += lz[i];
		lz[i] = 0;
	}
}
void build(int i, int l, int r) {
	lz[i] = 0, c[i] = -1;
	if(l == r) { mx[i] = w[seq[l]]; return; }
	int mid = (l + r) >> 1;
	build(ls, l, mid);
	build(rs, mid+1, r);
	upd(i);
}
void modify(int i, int l, int r, int x, int y, int val) {
	if(l == x && r == y) {
		mx[i] += val, lz[i] += val;
		return;
	}
	int mid = (l + r) >> 1;
	mt(i);
	if(y <= mid) modify(ls, l, mid, x, y, val);
	else if(x > mid) modify(rs, mid+1, r, x, y, val);
	else modify(ls, l, mid, x, mid, val), modify(rs, mid+1, r, mid+1, y, val);
	upd(i);
}
void cover(int i, int l, int r, int x, int y, int val) {
	if(l == x && r == y) {
		mx[i] = c[i] = val; lz[i] = 0;
		return;
	}
	int mid = (l + r) >> 1;
	mt(i);
	if(y <= mid) cover(ls, l, mid, x, y, val);
	else if(x > mid) cover(rs, mid+1, r, x, y, val);
	else cover(ls, l, mid, x, mid, val), cover(rs, mid+1, r, mid+1, y, val);
	upd(i);
}
int query(int i, int l, int r, int x, int y) {
	if(l == x && r == y) return mx[i];
	int mid = (l + r) >> 1, res = 0;
	mt(i);
	if(y <= mid) res = query(ls, l, mid, x, y);
	else if(x > mid) res = query(rs, mid+1, r, x, y);
	else res = max(query(ls, l, mid, x, mid), query(rs, mid+1, r, mid+1, y));
	upd(i);
	return res;
}
inline int Max(int x, int y) {
	int res = 0;
	while(top[x] != top[y]) {
		if(dep[top[x]] < dep[top[y]]) swap(x, y);
		res = max(res, query(1, 1, n, dfn[top[x]], dfn[x]));
		x = fa[top[x]];
	}
	if(x == y) return res;
	if(dfn[x] < dfn[y]) swap(x, y);
	res = max(res, query(1, 1, n, dfn[y]+1, dfn[x]));
	return res;
}
inline void Add(int x, int y, int val) {
	while(top[x] != top[y]) {
		if(dep[top[x]] < dep[top[y]]) swap(x, y);
		modify(1, 1, n, dfn[top[x]], dfn[x], val);
		x = fa[top[x]];
	}
	if(x == y) return;
	if(dfn[x] < dfn[y]) swap(x, y);
	modify(1, 1, n, dfn[y]+1, dfn[x], val);
}
inline void Cover(int x, int y, int val) {
	while(top[x] != top[y]) {
		if(dep[top[x]] < dep[top[y]]) swap(x, y);
		cover(1, 1, n, dfn[top[x]], dfn[x], val);
		x = fa[top[x]];
	}
	if(x == y) return;
	if(dfn[x] < dfn[y]) swap(x, y);
	cover(1, 1, n, dfn[y]+1, dfn[x], val);
}
int main() {
	memset(fir, -1, sizeof fir);
	read(n);
	for(int i = 1, x, y, z; i < n; ++i)
		read(x), read(y), read(z), add(x, y, z, i);
	dfs(1, 0); dfs2(1, 1);
	build(1, 1, n);
	char s[2]; int x, y, z;
	while(1) {
		while(!isalpha(s[0]=getchar())); s[1] = getchar();
		if(s[0] == 'S') return 0;
		read(x), read(y);
		if(s[0] == 'M') printf("%d\n", Max(x, y));
		else if(s[0] == 'A') read(z), Add(x, y, z);
		else if(s[0] == 'C' && s[1] == 'o') read(z), Cover(x, y, z);
		else Cover(fa[bel[x]], bel[x], y);
	}
}