BZOJ 2836: 魔法树 (树链剖分+线段树)

板题…记得开longlong

#include <cstdio>
#include <cctype>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long LL;
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, m, cnt, tmr, fir[MAXN], fa[MAXN], dfn[MAXN], top[MAXN], sz[MAXN], son[MAXN], dep[MAXN];
struct edge { int to, nxt; }e[MAXN];
inline void Add(int u, int v) {
	e[cnt] = (edge){ v, fir[u] }, fir[u] = cnt++;
}
void dfs(int x) {
	dep[x] = dep[fa[x]] + (sz[x]=1);
	for(int v, i = fir[x]; ~i; i = e[i].nxt) {
		fa[v=e[i].to] = x, dfs(v), sz[x] += sz[v];
		if(sz[v] > sz[son[x]]) son[x] = v;
	}
}
void dfs2(int x, int tp) {
	top[x] = tp; dfn[x] = ++tmr;
	if(son[x]) dfs2(son[x], tp);
	for(int v, i = fir[x]; ~i; i = e[i].nxt)
		if((v=e[i].to) != son[x]) dfs2(v, v);
}

namespace SegmentTree {
	LL sum[MAXN<<2], lz[MAXN<<2]; int l[MAXN<<2], r[MAXN<<2];
	inline void update(int i) {
		sum[i] = sum[i<<1] + sum[i<<1|1];
	}
	inline void pushdown(int i) {
		if(lz[i]) {
			lz[i<<1] += lz[i], lz[i<<1|1] += lz[i];
			sum[i<<1] += lz[i] * (r[i<<1] - l[i<<1] + 1);
			sum[i<<1|1] += lz[i] * (r[i<<1|1] - l[i<<1|1] + 1);
			lz[i] = 0;
		}
	}
	void build(int i, int x, int y) {
		l[i] = x, r[i] = y;
		if(x == y) return;
		int mid = (x + y) >> 1;
		build(i<<1, x, mid);
		build(i<<1|1, mid+1, y);
	}
	void insert(int i, int x, int y, int val) {
		if(l[i] == x && r[i] == y) {
			sum[i] += val * (y - x + 1);
			lz[i] += val;
			return;
		}
		pushdown(i);
		int mid = (l[i] + r[i]) >> 1;
		if(y <= mid) insert(i<<1, x, y, val);
		else if(x > mid) insert(i<<1|1, x, y, val);
		else insert(i<<1, x, mid, val), insert(i<<1|1, mid+1, y, val);
		update(i);
	}
	LL querysum(int i, int x, int y) {
		if(l[i] == x && r[i] == y) return sum[i];
		pushdown(i);
		LL mid = (l[i] + r[i]) >> 1, res = 0;
		if(y <= mid) res = querysum(i<<1, x, y);
		else if(x > mid) res = querysum(i<<1|1, x, y);
		else res = querysum(i<<1, x, mid) + querysum(i<<1|1, mid+1, y);
		update(i);
		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);
		SegmentTree::insert(1, dfn[top[x]], dfn[x], val);
		x = fa[top[x]];
	}
	if(dep[x] < dep[y]) swap(x, y);
	SegmentTree::insert(1, dfn[y], dfn[x], val);
}

int main() {
	memset(fir, -1, sizeof fir);
	read(n);
	for(int x, y, i = 1; i < n; ++i)
		read(x), read(y), Add(x+1, y+1);
	dfs(1); dfs2(1, 1);
	SegmentTree::build(1, 1, n);
	read(m);
	int x, y, z; char s[2];
	while(m--) {
		while(!isalpha(s[0]=getchar()));
		if(s[0] == 'A') read(x), read(y), read(z), Add(x+1, y+1, z);
		else read(x), printf("%lld\n", SegmentTree::querysum(1, dfn[x+1], dfn[x+1]+sz[x+1]-1));
	}
}