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| #include <iostream>
#include <cstdio>
using namespace std;
const int N = 1e5 + 10, M = 2e5 + 10;
int n, m, rt, w[N], d[N], p[N];
int idx, hd[N], nxt[M], edg[M];
int stmp, sz[N], son[N], top[N], rnk[N], dfn[N];
struct Node
{
int l, r, tag;
int s, lc, rc;
} tr[N << 2];
void pushup(int x)
{
tr[x].s = tr[x << 1].s + tr[x << 1 | 1].s;
if (tr[x << 1].rc == tr[x << 1 | 1].lc)
tr[x].s--;
tr[x].lc = tr[x << 1].lc;
tr[x].rc = tr[x << 1 | 1].rc;
}
void pushdown(int x)
{
tr[x << 1].s = tr[x << 1 | 1].s = 1;
tr[x << 1].lc = tr[x << 1].rc = tr[x].tag;
tr[x << 1 | 1].lc = tr[x << 1 | 1].rc = tr[x].tag;
tr[x << 1].tag = tr[x << 1 | 1].tag = tr[x].tag;
tr[x].tag = 0;
}
void build(int x, int l, int r)
{
tr[x].l = l;
tr[x].r = r;
if (l == r)
{
tr[x].s = 1;
tr[x].lc = tr[x].rc = w[rnk[l]];
return;
}
int mid = l + r >> 1;
build(x << 1, l, mid);
build(x << 1 | 1, mid + 1, r);
pushup(x);
}
void modify(int x, int l, int r, int k)
{
if (tr[x].l >= l && tr[x].r <= r)
{
tr[x].s = 1;
tr[x].lc = tr[x].rc = k;
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);
pushup(x);
}
Node query(int x, int l, int r)
{
if (tr[x].l >= l && tr[x].r <= r)
return tr[x];
if (tr[x].tag)
pushdown(x);
int mid = tr[x].l + tr[x].r >> 1;
if (r <= mid)
return query(x << 1, l, r);
else if (l > mid)
return query(x << 1 | 1, l, r);
Node res, lres = query(x << 1, l, r), rres = query(x << 1 | 1, l, r);
res.lc = lres.lc, res.rc = rres.rc, res.s = lres.s + rres.s;
if (lres.rc == rres.lc)
res.s--;
return res;
}
void ModifyPath(int x, int y, int 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);
}
int QueryPath(int x, int y)
{
int res = 0, xlc = -1, ylc = -1;
while (top[x] != top[y])
{
if (d[top[x]] > d[top[y]])
{
Node q = query(1, dfn[top[x]], dfn[x]);
res += q.s;
if (xlc == q.rc)
res--;
xlc = q.lc;
x = p[top[x]];
}
else
{
Node q = query(1, dfn[top[y]], dfn[y]);
res += q.s;
if (ylc == q.rc)
res--;
ylc = q.lc;
y = p[top[y]];
}
}
if (d[x] > d[y])
{
swap(x, y);
swap(xlc, ylc);
}
Node q = query(1, dfn[x], dfn[y]);
res += q.s;
if (xlc == q.lc)
res--;
if (ylc == q.rc)
res--;
return res;
}
void dfs1(int x)
{
son[x] = -1;
sz[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)
{
top[x] = t;
dfn[x] = ++stmp;
rnk[stmp] = x;
if (son[x] == -1)
return;
dfs2(son[x], t);
for (int i = hd[x]; ~i; i = nxt[i])
if (edg[i] != son[x] && edg[i] != p[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%d", &n, &m);
for (int i = 1; i <= n; i++)
hd[i] = -1;
for (int i = 1; i <= n; i++)
scanf("%d", &w[i]);
for (int i = 1, u, v; i < n; i++)
{
scanf("%d%d", &u, &v);
add(u, v);
add(v, u);
}
d[rt = 1] = 1;
dfs1(rt);
dfs2(rt, rt);
build(1, 1, n);
for (char op; m; m--)
{
scanf("%c", &op);
while (op != 'C' && op != 'Q')
scanf("%c", &op);
if (op == 'C')
{
int a, b, c;
scanf("%d%d%d", &a, &b, &c);
ModifyPath(a, b, c);
}
if (op == 'Q')
{
int a, b;
scanf("%d%d", &a, &b);
printf("%d\n", QueryPath(a, b));
}
}
return 0;
}
|