树链剖分学习
参考代码：
#include <cstdio>
#include <algorithm>
#include <iostream>
#include <vector>
#include <map>
#include <queue>
#include <set>
#include <ctime>
#include <cstring>
#include <cstdlib>
#include <math.h>
using namespace std;
typedef long long ll;
const int N = 1005;
const int maxn = 1e6 + 5;
struct node
{
int v, nex;
} edge[maxn << 1];
int head[maxn], w[maxn], son[maxn], deep[maxn];
int pre[maxn], sizx[maxn], dfn[maxn], top[maxn], a[maxn];
int cnt, cnx;
void add(int u, int v)
{
edge[cnt].v = v, edge[cnt].nex = head[u];
head[u] = cnt++;
}
void dfs1(int u, int fa)
{
pre[u] = fa;
deep[u] = deep[fa] + 1;
sizx[u] = 1;
int maxson = -1;
for (int i = head[u]; ~i; i = edge[i].nex)
{
int v = edge[i].v;
if (v != fa)
{
dfs1(v, u);
sizx[u] += sizx[v];
if (maxson < sizx[v])
{
son[u] = v;
maxson = sizx[v];
}
}
}
}
void dfs2(int u, int t)
{
top[u] = t;
dfn[u] = ++cnx;
a[cnx] = w[u];
if (!son[u])
return;
dfs2(son[u], t);
for (int i = head[u]; ~i; i = edge[i].nex)
{
int v = edge[i].v;
if (v != pre[u] && v != son[u])
{
dfs2(v, v);
}
}
}
struct vain
{
int l, r, p, lazy;
} tr[maxn << 2];
void pushdown(int k)
{
if (tr[k].lazy)
{
tr[k << 1].p += tr[k].lazy;
tr[k << 1 | 1].p += tr[k].lazy;
tr[k << 1].lazy += tr[k].lazy;
tr[k << 1 | 1].lazy += tr[k].lazy;
tr[k].lazy = 0;
}
}
void build(int k, int l, int r)
{
tr[k].l = l, tr[k].r = r, tr[k].lazy = 0;
if (l == r)
{
tr[k].p = a[l];
return;
}
int mid = l + r >> 1;
build(k << 1, l, mid);
build(k << 1 | 1, mid + 1, r);
}
void modify(int k, int ql, int qr, int w)
{
if (tr[k].l >= ql && tr[k].r <= qr)
{
tr[k].p += w;
tr[k].lazy += w;
return;
}
pushdown(k);
int mid = tr[k].l + tr[k].r >> 1;
if (ql <= mid)
{
modify(k << 1, ql, qr, w);
}
if (qr > mid)
{
modify(k << 1 | 1, ql, qr, w);
}
}
int query(int k, int pos)
{
if (tr[k].l == tr[k].r)
{
return tr[k].p;
}
pushdown(k);
int mid = tr[k].l + tr[k].r >> 1;
if (mid >= pos)
return query(k << 1, pos);
else
return query(k << 1 | 1, pos);
}
void swap(int &x, int &y)
{
int tep = x;
x = y, y = tep;
}
void mtre(int x, int y, int z)
{
while (top[x] != top[y])
{
if (deep[top[x]] < deep[top[y]])
swap(x, y);
modify(1, dfn[top[x]], dfn[x], z);
x = pre[top[x]];
}
if (deep[x] > deep[y])
swap(x, y);
modify(1, dfn[x], dfn[y], z);
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
int n, m, q;
while (cin >> n >> m >> q)
{
memset(son, 0, sizeof son);
memset(head, -1, sizeof head);
cnx = cnt = 0;
int u, v;
for (int i = 1; i <= n; i++)
cin >> w[i];
for (int i = 0; i < m; i++)
{
cin >> u >> v;
add(u, v), add(v, u);
}
dfs1(1, 0);
dfs2(1, 1);
build(1, 1, n);
while (q--)
{
char c;
cin >> c;
if (c == 'I')
{
int u, v, w;
cin >> u >> v >> w;
mtre(u, v, w);
}
if (c == 'D')
{
int u, v, w;
cin >> u >> v >> w;
mtre(u, v, -w);
}
if (c == 'Q')
{
int p;
cin >> p;
cout << query(1, dfn[p]) << endl;
}
}
}
}