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| // @Title: 最小体力消耗路径 (Path With Minimum Effort)
// @Author: 15816537946@163.com
// @Date: 2021-01-29 21:14:07
// @Runtime: 160 ms
// @Memory: 8.1 MB
type unionFind struct {
parent, size []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}
}
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
}
func (uf *unionFind) inSameSet(x, y int) bool {
return uf.find(x) == uf.find(y)
}
type edge struct {
v, w, diff int
}
func minimumEffortPath(heights [][]int) int {
n, m := len(heights), len(heights[0])
edges := []edge{}
for i, row := range heights {
for j, h := range row {
id := i*m + j
if i > 0 {
edges = append(edges, edge{id - m, id, abs(h - heights[i-1][j])})
}
if j > 0 {
edges = append(edges, edge{id - 1, id, abs(h - heights[i][j-1])})
}
}
}
sort.Slice(edges, func(i, j int) bool { return edges[i].diff < edges[j].diff })
uf := newUnionFind(n * m)
for _, e := range edges {
uf.union(e.v, e.w)
if uf.inSameSet(0, n*m-1) {
return e.diff
}
}
return 0
}
func abs(x int) int {
if x < 0 {
return -x
}
return x
}
|