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| // @Title: 情侣牵手 (Couples Holding Hands)
// @Author: 15816537946@163.com
// @Date: 2021-02-14 21:37:52
// @Runtime: 0 ms
// @Memory: 2 MB
// 并查集,情人节撒狗粮呢
type unionFind struct {
parent, size []int
setCount int // 当前连通分量数目
}
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 minSwapsCouples(row []int) int {
n := len(row)
uf := newUnionFind(n / 2)
for i := 0; i < n; i += 2 {
uf.union(row[i]/2, row[i+1]/2)
}
return n/2 - uf.setCount
}
|