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每个点有一个权值.并查集.在集合合并的过程中查询集合第k大.
并查集,每个点开个线段树.然后在并查集集合合并的过程中同时线段树合并即可.
AC代码:
#includeusing namespace std;#define mid ((l + r) >> 1)const int maxn = 1e5 + 5;int sum[maxn << 5] , ls[maxn << 5] , rs[maxn << 5] , rt[maxn] , tot;void pushup (int t){ int tl = ls[t] , tr = rs[t]; sum[t] = sum[tl] + sum[tr];}int add (int l , int r , int t , int p , int c){ int now = ++tot; ls[now] = ls[t]; rs[now] = rs[t]; if (l == r) { sum[now] += c; return now; } if (p <= mid) ls[now] = add(l , mid , ls[now] , p , c); else rs[now] = add(mid + 1 , r , rs[now] , p , c); pushup(now); return now;}int ask (int l , int r , int t , int k){ if (l == r) return l; if (sum[ls[t]] >= k) return ask(l , mid , ls[t] , k); return ask(mid + 1 , r , rs[t] , k - sum[ls[t]]);}int mer (int a , int b , int l , int r){ if (!a) return b; if (!b) return a; if (l == r) { sum[a] += sum[b]; return a; } ls[a] = mer (ls[a] , ls[b] , l , mid); rs[a] = mer (rs[a] , rs[b] , mid + 1 , r); pushup(a); return a;}int a[maxn] , f[maxn] , n , m , id[maxn];int getf (int x){ return f[x]==x?x:f[x]=getf(f[x]);}int dsu_mer (int a , int b){ int fa = getf(a) , fb = getf(b); if (fa == fb) return false; f[fb] = fa; mer(rt[fa] , rt[fb] , 1 , n); return true;}int main(){ scanf("%d%d" , &n , &m); for (int i = 1; i <= n ; i++){ scanf("%d" , a + i); id[a[i]] = i; f[i] = i; rt[i] = add(1 , n , rt[0] , a[i] , 1); } for (int i = 1; i <= m ; i++){ int x , y; scanf("%d%d" , &x , &y); dsu_mer (x , y); } char op[5]; int x , y , q;scanf("%d" , &q); for (int i = 1; i <= q ; i++){ scanf("%s" , op); scanf("%d%d" , &x , &y); if (op[0] == 'Q'){ x = getf (x); if (sum[rt[x]] < y){ printf("-1\n"); }else { printf("%d\n" , id[ask(1 , n , rt[x] , y)]); } }else { dsu_mer (x , y); } } return 0;}
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