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| #include <bits/stdc++.h>
using namespace std;
const int MaxN = 300010;
int n, m, val[MaxN], p[MaxN], q[MaxN], war;
struct Link_Cut_Tree
{
int top, ch[MaxN][2], fa[MaxN], sum[MaxN], q[MaxN], rev[MaxN];
inline void pushup(int x) { sum[x] = sum[ch[x][0]] ^ sum[ch[x][1]] ^ val[x]; }
inline void pushdown(int x)
{
int l = ch[x][0], r = ch[x][1];
if (rev[x])
{
rev[l] ^= 1;
rev[r] ^= 1;
rev[x] ^= 1;
swap(ch[x][0], ch[x][1]);
}
}
inline bool isroot(int x) { return ch[fa[x]][0] != x && ch[fa[x]][1] != x; }
void rotate(int x)
{
int y = fa[x], z = fa[y], l, r;
if (ch[y][0] == x)
l = 0;
else
l = 1;
r = l ^ 1;
if (!isroot(y))
{
if (ch[z][0] == y)
ch[z][0] = x;
else
ch[z][1] = x;
}
fa[x] = z;
fa[y] = x;
fa[ch[x][r]] = y;
ch[y][l] = ch[x][r], ch[x][r] = y;
pushup(y), pushup(x);
}
void splay(int x)
{
top = 1;
q[top] = x;
for (int i = x; !isroot(i); i = fa[i])
q[++top] = fa[i];
for (int i = top; i; i--)
pushdown(q[i]);
while (!isroot(x))
{
int y = fa[x], z = fa[y];
if (!isroot(y))
{
if ((ch[y][0] == x) ^ (ch[z][0] == y))
rotate(x);
else
rotate(y);
}
rotate(x);
}
}
void access(int x)
{
for (int t = 0; x; t = x, x = fa[x])
splay(x), ch[x][1] = t, pushup(x);
}
void makeroot(int x)
{
access(x);
splay(x);
rev[x] ^= 1;
}
int find(int x)
{
access(x);
splay(x);
while (ch[x][0])
x = ch[x][0];
return x;
}
void split(int x, int y)
{
makeroot(x);
access(y);
splay(y);
}
void cut(int x, int y)
{
makeroot(x);
if (find(y) != x || fa[x] != y || ch[x][1])
return;
fa[x] = ch[y][0] = 0;
pushup(y);
}
void link(int x, int y)
{
makeroot(x);
fa[x] = y;
}
} t;
int main()
{
scanf("%d%d", &n, &m);
for(int i = 1; i < n; i++)
{
int u, v;
scanf("%d%d", &u, &v);
t.link(u, v);
}
for(int i = 1; i <= m; i++)
{
std::string op;
std::cin >> op;
if(op == "Q")
{
int x, y;
scanf("%d%d", &x, &y);
int fx = t.find(x), fy = t.find(y);
if(fx == fy)
printf("Yes\n");
else printf("No\n");
}
else if(op == "C")
{
++war;
scanf("%d%d", &p[war], &q[war]);
t.cut(p[war], q[war]);
}
else
{
int x;
scanf("%d", &x);
t.link(p[x], q[x]);
}
}
return 0;
}
|