Portal

要求维护一个可以支持断开树边的并查集。

\[ n <= 10000, m <= 200009 \]

LCT的最普通的应用。 直接上模板就好了。

#include<bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for(int i = (a), i##_end_ = (b); i <= i##_end_; ++i)
#define drep(i, a, b) for(int i = (a), i##_end_ = (b); i >= i##_end_; --i)
#define clar(a, b) memset((a), (b), sizeof(a))
#define debug(...) fprintf(stderr, __VA_ARGS__)
#define pass {if (true){;}}
typedef long long LL;
typedef long double LD;
int read() {
    char ch = getchar();
    int x = 0, flag = 1;
    for (;!isdigit(ch); ch = getchar()) if (ch == '-') flag *= -1;
    for (;isdigit(ch); ch = getchar()) x = x * 10 + ch - 48;
    return x * flag;
}
void write(int x) {
    if (x < 0) putchar('-'), x = -x;
    if (x >= 10) write(x / 10);
    putchar(x % 10 + 48);
}

template <int N> struct LCT {
    struct node {
        int fa, ch[2], revTag, size, wide;
    }t[N];  
    int _top, stk[N];

#define fa(x) (t[(x)].fa)
#define lc(x) (t[(x)].ch[0])
#define rc(x) (t[(x)].ch[1])

    inline bool isroot(int rt) { return lc(fa(rt)) != rt && rc(fa(rt)) != rt; }
    void pushup(int rt) { 
        t[rt].size = t[lc(rt)].size + t[rc(rt)].size + 1; 
    }
    void setRev(int rt) { t[rt].revTag ^= 1, swap(lc(rt), rc(rt)); }
    void pushdown(int rt) {
        if (t[rt].revTag) {
            setRev(lc(rt)), setRev(rc(rt));
            t[rt].revTag = 0;
        }
    }   

    void rotate(int rt) {
        int y = fa(rt), z = fa(y), dir = (rc(y) == rt);
        if (!isroot(y)) t[z].ch[t[z].ch[1] == y] = rt; t[rt].fa = z;
        t[y].ch[dir] = t[rt].ch[dir ^ 1]; t[t[rt].ch[dir ^ 1]].fa = y;
        t[rt].ch[dir ^ 1] = y; t[y].fa = rt;
        pushup(y); pushup(rt);
    }

    void splay(int rt) {
        stk[_top = 1] = rt;
/**/    for (int u = rt; !isroot(u); u = fa(u)) stk[++_top] = fa(u);
        while (_top) pushdown(stk[_top--]);
        while (!isroot(rt)) {
            int y = fa(rt), z = fa(y);
/**//**/    if (!isroot(y))
                (t[z].ch[1] == y) ^ (t[y].ch[1] == rt) ? rotate(rt) : rotate(y);
            rotate(rt);
        }
        pushup(rt);
    }

    void access(int u) { for (int y = 0; u; u = t[y = u].fa) splay(u), t[u].ch[1] = y, pushup(u); }
    void makeRoot(int u) { access(u); splay(u); setRev(u); }
    int findRoot(int u) {
        access(u); splay(u);
        while (t[u].ch[0]) pushdown(u), u = t[u].ch[0];
        return u;
    }
    void spilt(int u, int v) { makeRoot(u); access(v); /*?*/ splay(v); }
    void link(int u, int v) { makeRoot(u); if (findRoot(u) != v) t[u].fa = v; }
    void cut(int u, int v) {
        spilt(u, v);
        if (findRoot(v) == u && t[u].fa == v && t[v].ch[0] == u) {
            t[u].fa = t[v].ch[0] = 0;
            pushup(v);
        }
    }
#undef fa                   
#undef lc
#undef rc
};

const int Maxn = 10009;
LCT <Maxn> s;
int n, m;

void init() {
    n = read(), m = read();
}

char Opt[19];
void solve() {
    while (m--) {
        scanf("%s", Opt);
        int u = read(), v = read();
        if (Opt[0] == 'C') s.link(u, v);
        if (Opt[0] == 'D') s.cut(u, v);
        if (Opt[0] == 'Q') puts(s.findRoot(u) == s.findRoot(v) ? "Yes" : "No");
    }
}

int main() {
    freopen("LG2147.in", "r", stdin);
    freopen("LG2147.out", "w", stdout);

    init();
    solve();

#ifdef Qrsikno
    debug("\nRunning time: %.3lf(s)\n", clock() * 1.0 / CLOCKS_PER_SEC);
#endif
    return 0;
}