github.com/whtcorpsinc/MilevaDB-Prod@v0.0.0-20211104133533-f57f4be3b597/soliton/disjointset/int_set.go (about)

     1  // Copyright 2020 WHTCORPS INC, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package disjointset
    15  
    16  // IntSet is the int disjoint set.
    17  type IntSet struct {
    18  	parent []int
    19  }
    20  
    21  // NewIntSet returns a new int disjoint set.
    22  func NewIntSet(size int) *IntSet {
    23  	p := make([]int, size)
    24  	for i := range p {
    25  		p[i] = i
    26  	}
    27  	return &IntSet{parent: p}
    28  }
    29  
    30  // Union unions two sets in int disjoint set.
    31  func (m *IntSet) Union(a int, b int) {
    32  	m.parent[m.FindRoot(a)] = m.FindRoot(b)
    33  }
    34  
    35  // FindRoot finds the representative element of the set that `a` belongs to.
    36  func (m *IntSet) FindRoot(a int) int {
    37  	if a == m.parent[a] {
    38  		return a
    39  	}
    40  	m.parent[a] = m.FindRoot(m.parent[a])
    41  	return m.parent[a]
    42  }