题面

Sol

\(LCT+\)并查集维护双联通分量，每次加边\(x，y\)，如果已经相连就把这条路径缩成一个点，赋上权值

\(LCT\)调用\(fa\)时一定要在并查集中\(find\)一下

细节很多，常数很大

# include 
    
     # define IL inline# define RG register# define ls ch[0][x]# define rs ch[1][x]# define Fill(a, b) memset(a, b, sizeof(a))using namespace std;typedef long long ll;const int _(2e5 + 10);IL ll Read(){    RG char c = getchar(); RG ll x = 0, z = 1;    for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;    for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);    return x * z;}int n, Q, ch[2][_], fa[_], sum[_], rev[_], S[_], val[_], scc[_], bel[_], w[_];IL int Find(RG int x){  return x == scc[x] ? x : scc[x] = Find(scc[x]);  }IL int _Find(RG int x){  return x == bel[x] ? x : bel[x] = _Find(bel[x]);  }IL bool Son(RG int x){  return ch[1][Find(fa[x])] == x;  }IL bool Isroot(RG int x){  RG int pa = Find(fa[x]); return ch[0][pa] != x && ch[1][pa] != x;  }IL void Reverse(RG int x){  if(!x) return; swap(ls, rs); rev[x] ^= 1;  }IL void Update(RG int x){  sum[x] = sum[ls] + sum[rs] + val[x];  }IL void Pushdown(RG int x){  if(!rev[x]) return; Reverse(ls); Reverse(rs); rev[x] = 0;  }IL void Rotate(RG int x){    RG int y = Find(fa[x]), z = Find(fa[y]), c = Son(x);    if(!Isroot(y)) ch[Son(y)][z] = x; fa[x] = z;    ch[c][y] = ch[!c][x]; fa[ch[c][y]] = y;    ch[!c][x] = y; fa[y] = x; Update(y);}IL void Splay(RG int x){    S[S[0] = 1] = x;    for(RG int y = x; !Isroot(y); y = Find(fa[y])) S[++S[0]] = Find(fa[y]);    while(S[0]) Pushdown(S[S[0]--]);    for(RG int y = Find(fa[x]); !Isroot(x); Rotate(x), y = Find(fa[x]))        if(!Isroot(y)) Son(x) ^ Son(y) ? Rotate(x) : Rotate(y);    Update(x);}IL void Access(RG int x){  for(RG int y = 0; x; y = x, x = Find(fa[x])) Splay(x), ch[1][x] = y, Update(x);  }IL void Makeroot(RG int x){  Access(x); Splay(x); Reverse(x);  }IL void Link(RG int x, RG int y){  Makeroot(x); fa[x] = y;  }IL void Split(RG int x, RG int y){  Makeroot(x); Access(y); Splay(y);  }IL void Dfs(RG int x, RG int y){  if(!x) return; scc[Find(x)] = y; Dfs(ls, y); Dfs(rs, y);  }int main(RG int argc, RG char* argv[]){    n = Read(); Q = Read();    for(RG int i = 1; i <= n; ++i) bel[i] = scc[i] = i, w[i] = val[i] = Read();    while(Q--){        RG int p = Read(), a = Read(), b = Read(), fx;        if(p == 1){            a = Find(a); b = Find(b);            if(_Find(a) != _Find(b)) Link(a, b), bel[_Find(a)] = _Find(b);            else{                Split(a, b); val[b] = sum[b];                Dfs(b, b);                ch[0][b] = ch[1][b] = 0;            }        }        else if(p == 2) fx = Find(a), Makeroot(fx), val[fx] += b - w[a], w[a] = b, Update(fx);        else{            a = Find(a); b = Find(b);            if(_Find(a) != _Find(b)){  puts("-1"); continue;  }            Split(a, b); printf("%d\n", sum[b]);        }    }    return 0;}