UnionFind

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      "#UnionFind"
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     "input": [
      "class unionfind(object):\n",
      "    def __init__(self, n):\n",
      "        self.parent = range(n)\n",
      "    def find(self, i):\n",
      "        if self.parent[i] != i: self.parent[i] = self.find(self.parent[i])\n",
      "        return self.parent[i]\n",
      "    def unite(self, i, j):\n",
      "        i = self.find(i)\n",
      "        j = self.find(j)\n",
      "        if i != j: self.parent[i] = j\n",
      "    def issame(self, i, j):\n",
      "        return self.find(i) == self.find(j)"
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http://nbviewer.ipython.org/gist/Tsutomu-KKE/dae823ed0549a296aba9