图及算法----并查集父亲查找写法比较 DisjointSet

1. 花式查找并查集

class DisjointSet:
    def __init__(self, n):
        # Args:
        #   n (int): Number of vertices in the graph

        self.parent = [None] * n  # Contains which node is the parent of the node at poisition <i>
        self.size = [1] * n  # Contains size of node at index <i>, used to optimize merge
        for i in range(n):
            self.parent[i] = i  # Make all nodes his own parent, creating n sets.


def find_set(self, a):
    if self.parent[a] != a: 
        # Very important, memoize result of the recursion in the list to optimize next
        # calls and make this operation practically constant, O(1)
        self.parent[a] = find_set(self.parent[a])

    # node <a> it's the set root, so we can return that index
    return self.parent[a]

     
def find_set2(self, a):
    parent_n = a
    parent_n1 = self.parent[parent_n]
    while parent_n1 != parent_n: 
        time.sleep(2)
        parent_n = parent_n1
        parent_n1 = self.parent[parent_n]
        print(parent_n1, parent_n, a)
    return parent_n1


def find_set3(self, a):
    visited, que = set(), [a]
    u = self.parent[a]
    while que: 
        time.sleep(2)
        u = que.pop()
        if u not in visited:
            print(f"u={u} was visited")
            visited.add(u)
            que.append(self.parent[u])
    return u


def find_set4(self, a):
    parent_n1 = a
    while 1: 
        time.sleep(2)
        parent_n = parent_n1
        parent_n1 = self.parent[parent_n]
        if parent_n1 == parent_n:
            break
        
        print(parent_n1, parent_n, a)
    return parent_n1


def find_set5(self, a):
    parent_n = a
    while 1: 
        time.sleep(2)
        parent_n1 = self.parent[parent_n]
        if parent_n1 == parent_n:
            break
        parent_n = parent_n1
        print(parent_n1, parent_n, a)
    return parent_n1


def find_set6(self, a):
    parent_n = a
    parent_n1 = self.parent[parent_n]
    while 1: 
        if parent_n1 != parent_n:  # 收敛条件
            break
        time.sleep(2)
        parent_n = parent_n1
        parent_n1 = self.parent[parent_n]
        print(parent_n1, parent_n, a)
    return parent_n1