1319, Number of operations to make network connected

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1319, Number of operations to make network connected

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Union find

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1. 給予n台電腦, matrix of connection

所以matrix size至少要大約等於n-1

2. 給予root(n)紀錄單元root

如果有描述的link, root[y] = x

3. 如果有相同的root

(redundant (count++

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class Solution:

vec<int> root(n)

public makeConnected(int n, vec<vec<int>>& con){

  int count=0, cable=con.size()

  if cable < n-1

    return -1

  else

    for i-n root[i] = I

    for i-n

      int x = getRoot(con[i][0])

      int y = getRoot(con[i][1])

      if x == y

        count++

      else

        root[y] = x

      return count

int getRoot(int i)

  if root[i] == I

    return i

  return getRoot(root[i])