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// @Title: 相似字符串组 (Similar String Groups)
// @Author: 15816537946@163.com
// @Date: 2021-01-31 11:47:33
// @Runtime: 8 ms
// @Memory: 4.2 MB

type unionFind struct {
	parent, size []int
	setCount     int
}

func newUnionFind(n int) *unionFind {
	parent := make([]int, n)
	size := make([]int, n)
	for i := range parent {
		parent[i] = i
		size[i] = 1
	}
	return &unionFind{parent, size, n}
}

func (uf *unionFind) find(x int) int {
	if uf.parent[x] != x {
		uf.parent[x] = uf.find(uf.parent[x])
	}
	return uf.parent[x]
}

func (uf *unionFind) union(x, y int) {
	fx, fy := uf.find(x), uf.find(y)
	if fx == fy {
		return
	}
	if uf.size[fx] < uf.size[fy] {
		fx, fy = fy, fx
	}
	uf.size[fx] += uf.size[fy]
	uf.parent[fy] = fx
	uf.setCount--
}

func (uf *unionFind) inSameSet(x, y int) bool {
	return uf.find(x) == uf.find(y)
}

func (uf *unionFind) isSimilar(s, t string) bool {
	diff := 0
	for i := range s {
		if s[i] != t[i] {
			diff++
		}
		if diff > 2 {
			return false
		}
	}
	return true
}

func numSimilarGroups(strs []string) int {
	n := len(strs)
	uf := newUnionFind(n)
	for i, s := range strs {
		for j := i + 1; j < n; j++ {
			if !uf.inSameSet(i, j) && uf.isSimilar(s, strs[j]) {
				uf.union(i, j)
			}
		}
	}

	return uf.setCount
}