社团检测seed选择Low conductance cuts
社团检测相关，虽然实现了seed的选择，但由于时间仓促，程序写的比较low，时间复杂度高！

function [ leader , ratio ] = isLeader2( adj)
%Reference:A Local Seed Selection Algorithm for Overlapping Community Detection
%@Author:xianyu
%Data:2019.2.26
%Disadvantage:high time complexity
%Input:networks adjacency matrix ( unweighted and undirected )
%Output:seed(leader),ratio(conductance)
leader = [];
n = size(adj,1);
neig = cell(1,n);
egonet = cell(1,n);
deg_v = zeros(1,n);
mid_adj = adj;
for i = 1:n
    mid_adj(i,i) = 1;
    index1 = find(mid_adj(i,:)==1);
    egonet(1,i) = {{index1}};          %egonet:v and the neighbors of v
    index2 = find(adj(i,:)==1);
    deg_v(1,i) = length(index2);       %the degree of each node
    neig(1,i) = {{index2}};            %the neighbors of each node 
end
col = zeros(3,n);
for i = 1:n
    for j = 1:n
        if find(mid_adj(i,j)==1)
            col(1,i) = col(1,i) + deg_v(1,j);
        else
            col(2,i) = col(2,i) + deg_v(1,j);
        end
    end
    col(3,i) = min(col(1,i), col(2,i));      %the denominator
end
mol = zeros(1,n);    %the molecular
for i = 1:n
    array = neig{1,i}{1,1};
    m = length(array);
    for j = 1:m
        x = array(1,j);
        for k = 1:n
            if (adj(x,k)==1 && k~= i && ~ismember(k,array))
                mol(1,i) = mol(1,i) + 1;
            end
        end
    end
end
ratio = zeros(1,n);
for i = 1:n
    ratio(1,i) = mol(1,i)/col(3,i);
end
for i = 1:n
    p = 0;             %the counter
    array = neig{1,i}{1,1};
    m = length(array);
    for j = 1:m
        x = array(1,j);
        if ratio(1,i) > ratio(1,x)
            break;
        else
            p = p + 1;
        end
    end
    if p == m
        leader = [leader;i];
    end
end
end