Blog of RuSun

\begin {array}{c} \mathfrak {One Problem Is Difficult} \\\\ \mathfrak {Because You Don't Know} \\\\ \mathfrak {Why It Is Diffucult} \end {array}

CF343D Water Tree

LuoGu: CF343D Water Tree

CF: D. Water Tree

水题。

查看代码
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#include <cstdio>
#include <algorithm>
using namespace std;
const int N = 5e5 + 10, M = N << 1;
int n, m, p[N], d[N], sz[N];
int stmp, dfn[N], son[N], top[N];
int idx, hd[N], nxt[M], edg[M];
struct Node
{
int tag;
int l, r, v;
} tr[N << 2];
void pushdown(int x)
{
tr[x << 1].v = tr[x << 1 | 1].v = tr[x].tag;
tr[x << 1].tag = tr[x << 1 | 1].tag = tr[x].tag;
tr[x].tag = -1;
}
void build(int x, int l, int r)
{
tr[x].l = l, tr[x].r = r;
tr[x].tag = -1;
if (l == r)
return;
int mid = l + r >> 1;
build(x << 1, l, mid);
build(x << 1 | 1, mid + 1, r);
}
void modify(int x, int l, int r, bool k)
{
if (tr[x].l >= l && tr[x].r <= r)
{
tr[x].v = tr[x].tag = k;
return;
}
if (~tr[x].tag)
pushdown(x);
int mid = tr[x].l + tr[x].r >> 1;
if (l <= mid)
modify(x << 1, l, r, k);
if (r > mid)
modify(x << 1 | 1, l, r, k);
}
int query(int x, int t)
{
if (tr[x].l == tr[x].r)
return tr[x].v;
if (~tr[x].tag)
pushdown(x);
int mid = tr[x].l + tr[x].r >> 1;
if (t <= mid)
return query(x << 1, t);
return query(x << 1 | 1, t);
}
void ModifyPath(int x, int y, bool k)
{
while (top[x] != top[y])
{
if (d[top[x]] < d[top[y]])
swap(x, y);
modify(1, dfn[top[x]], dfn[x], k);
x = p[top[x]];
}
if (d[x] > d[y])
swap(x, y);
modify(1, dfn[x], dfn[y], k);
}
void ModifyTree(int x, int k)
{
modify(1, dfn[x], dfn[x] + sz[x] - 1, k);
}
void dfs1(int x)
{
sz[x] = 1;
son[x] = -1;
for (int i = hd[x]; ~i; i = nxt[i])
if (!d[edg[i]])
{
d[edg[i]] = d[x] + 1;
p[edg[i]] = x;
dfs1(edg[i]);
sz[x] += sz[edg[i]];
if (son[x] == -1 || sz[edg[i]] > sz[son[x]])
son[x] = edg[i];
}
}
void dfs2(int x, int t)
{
dfn[x] = ++stmp;
top[x] = t;
if (~son[x])
dfs2(son[x], t);
for (int i = hd[x]; ~i; i = nxt[i])
if (edg[i] != p[x] && edg[i] != son[x])
dfs2(edg[i], edg[i]);
}
void add(int a, int b)
{
nxt[++idx] = hd[a];
hd[a] = idx;
edg[idx] = b;
}
int main()
{
scanf("%d", &n);
for (int i = 1; i <= n; i++)
hd[i] = -1;
for (int i = 1, u, v; i < n; i++)
{
scanf("%d%d", &u, &v);
add(u, v);
add(v, u);
}
d[1] = 1;
dfs1(1);
dfs2(1, 1);
build(1, 1, n);
scanf("%d", &m);
for (int op, x; m; m--)
{
scanf("%d%d", &op, &x);
if (op == 1)
ModifyTree(x, 1);
else if (op == 2)
ModifyPath(1, x, 0);
else if (op == 3)
printf("%d\n", query(1, dfn[x]));
}
return 0;
}