HDU - 3966 Aragorn's Story(树剖模版题)

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;
const int N = 50005;
inline int lowbit(int x) {return x & (-x); }

int dep
, f
, son
, size
, top
, id
, bit
, val
, idx;
int n, m, p;
vector<int> g
;

//dep存储的是节点的深度
//size记录的是以u为根结点的子树的节点数
//f数组记录的是每个节点的父节点
//son记录的是与u同在一重链上的u的子节点
//初始值1, -1, 1

void dfs1(int u, int fa, int depth) {
dep[u] = depth;
size[u] = 1;
f[u] = fa;
son[u] = 0;
for (int i = 0; i < g[u].size(); i++) {
int v = g[u][i];
if (v == fa) continue;
dfs1(v, u, depth + 1);
size[u] += size[v];
if (size[son[u]] < size[v]) son[u] = v;
}
}

//top记录的是结点所在的链的顶端结点
//id记录的是树的结点对应的的值
//初始值是1,1

void dfs2(int u, int tp) {
id[u] = ++idx;
top[u] = tp;
//son[u]是重链
if (son[u]) dfs2(son[u], tp);
for (int i = 0; i < g[u].size(); i++) {
int v = g[u][i];
if (v == f[u] || v == son[u]) continue;
dfs2(v, v);
}
}

void add(int x, int v) {
while (x < N) {
bit[x] += v;
x += lowbit(x);
}
}

void add(int l, int r, int v) {
add(l, v);
add(r + 1, -v);
}

void gao(int u, int v, int w) {
int tp1 = top[u], tp2 = top[v];
while (tp1 != tp2) {
if (dep[tp1] < dep[tp2]) {
swap(tp1, tp2);
swap(u, v);
}
add(id[tp1], id[u], w);
u = f[tp1];
tp1 = top[u];
}
if (dep[u] > dep[v]) swap(u, v);
add(id[u], id[v], w);
}

int query(int x) {
int ans = 0;
while (x) {
ans += bit[x];
x -= lowbit(x);
}
return ans;
}

int main() {
while (scanf("%d%d%d", &n, &m, &p) != EOF) {
idx = 0;
memset(bit, 0, sizeof(bit));
for (int i = 1; i <= n; i++) {
scanf("%d", &val[i]);
g[i].clear();
}

int u, v;
while (m--) {
scanf("%d%d", &u, &v);
g[u].push_back(v);
g[v].push_back(u);
}
dfs1(1, -1, 1);
dfs2(1, 1);
for (int i = 1; i <= n; i++) add(id[i], id[i], val[i]);
char q[2];
int a, b, c;
while (p--) {
scanf("%s", q);
if (q[0] == 'I' || q[0] == 'D') {
scanf("%d%d%d", &a, &b, &c);
if (q[0] == 'D') c = -c;
gao(a, b, c);
}
else {
scanf("%d", &a);
printf("%d\n", query(id[a]));
}
}
}
return 0;
}