/
minCostToConnectAllPoints.go
88 lines (78 loc) · 1.41 KB
/
minCostToConnectAllPoints.go
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package _021_07
import "sort"
// Min Cost to Connect All Points
// leetcode: https://leetcode-cn.com/problems/min-cost-to-connect-all-points/
type unionFind struct {
parent, rank []int
}
func newUnionFind(n int) *unionFind {
parent := make([]int, n)
rank := make([]int, n)
for i := range parent {
parent[i] = i
rank[i] = i
}
return &unionFind{
parent,
rank,
}
}
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) bool {
fx, fy := uf.find(x), uf.find(y)
if fx == fy {
return false
}
if uf.rank[x] < uf.rank[y] {
fx, fy = fy, fx
}
uf.rank[fx] += uf.rank[fy]
uf.parent[fy] = fx
return true
}
func distance(a, b []int) int {
return abs(a[0] - b[0]) + abs(a[1] - b[1])
}
func MinCostToConnectAllPoints(points [][]int) int {
n := len(points)
ans := 0
type edge struct {
v, w, dis int
}
var edges []edge
for i, p := range points {
for j := i + 1; j < n; j++ {
edges = append(edges, edge{
v: i,
w: j,
dis: distance(p, points[j]),
})
}
}
sort.Slice(edges, func(i, j int) bool {
return edges[i].dis < edges[j].dis
})
uf := newUnionFind(n)
left := n-1
for _, edge := range edges {
if uf.union(edge.v, edge.w) {
ans += edge.dis
left--
if left == 0 {
return ans
}
}
}
return ans
}
func abs(n int) int {
if n < 0 {
return -n
}
return n
}