[英]Union/find algorithm without union by rank for disjoint-set forests data structure
[英]Disjoint-Set (union-find) data structure in MATLAB
MATLAB 中是否有聯合查找算法的任何實現?
如果沒有,是否可以使用 classdef 或任何其他方法來實現它?
我在網上看了很多,找不到任何 MATLAB 的實現! 這是我能問的最后一個地方,一只手會很棒!
提前致謝
一個不相交的集合可以通過使用向量來實現。 a[u] = ancestor of node u
。
我的實現,使用路徑減半和大小聯合來限制樹的高度(沒有很好的測試):
classdef DJSet < handle
properties
N; root;size;
end
methods
function obj=DJSet(n)
obj.N = n;
obj.root = 1:n;
obj.size = ones(1,n);
end
function root = find(obj, u)
while obj.root(u) ~= u
obj.root(u) = obj.root(obj.root(u));
u = obj.root(u);
end
root = u;
end
function union(obj, u, v)
root_u = obj.find(u);
root_v = obj.find(v);
if root_u == root_v
return;
end
if obj.size(root_u) < obj.size(root_v)
obj.root(root_u) = root_v;
obj.size(root_v) = obj.size(root_v) + obj.size(root_u);
else
obj.root(root_v) = root_u;
obj.size(root_u) = obj.size(root_u) + obj.size(root_v);
end
end
function res = is_connected(obj, u, v)
root_u = obj.find(u);
root_v = obj.find(v);
res = root_u == root_v;
end
end
end
測試用例:
dj=DJSet(10);
edges = [1 2; 3 4; 5 6; 7 8; 2 3; 1 3; 6 7];
for i = 1:size(edges,1)
dj.union(edges(i,1), edges(i,2));
end
for j = 2:10
fprintf('%d and %d connection is %d\n', 1, j, dj.is_connected(1, j));
end
dj.union(3,6);
fprintf('#####\nAfter connecting 3 and 6\n')
for j = 2:10
fprintf('%d and %d connection is %d\n', 1, j, dj.is_connected(1, j));
end
>> test
1 and 2 connection is 1
1 and 3 connection is 1
1 and 4 connection is 1
1 and 5 connection is 0
1 and 6 connection is 0
1 and 7 connection is 0
1 and 8 connection is 0
1 and 9 connection is 0
1 and 10 connection is 0
#####
After connecting 3 and 6
1 and 2 connection is 1
1 and 3 connection is 1
1 and 4 connection is 1
1 and 5 connection is 1
1 and 6 connection is 1
1 and 7 connection is 1
1 and 8 connection is 1
1 and 9 connection is 0
1 and 10 connection is 0
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