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solution.go
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solution.go
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package regions_cut_by_slashes
func RegionsBySlashes(grid []string) int {
n := len(grid)
if n < 1 {
return 0
}
d := newDisjointSet(n * n * 4)
for i, line := range grid {
for j := 0; j < len(line); j++ {
base := 4 * (n*i + j)
switch line[j] {
case ' ':
d.union(base, base+1)
d.union(base, base+2)
d.union(base, base+3)
case '/':
d.union(base, base+3)
d.union(base+1, base+2)
case '\\':
d.union(base, base+1)
d.union(base+2, base+3)
}
if i < n-1 {
d.union(base+2, base+4*n)
}
if j < n-1 {
d.union(base+1, base+7)
}
}
}
return d.counter
}
type disjointSet struct {
inner []int
counter int
}
func newDisjointSet(size int) *disjointSet {
inner := make([]int, size)
for i := range inner {
inner[i] = i
}
return &disjointSet{inner, size}
}
func (d *disjointSet) find(i int) int {
parent := &d.inner[i]
if *parent != i {
*parent = d.find(*parent)
}
return *parent
}
func (d *disjointSet) union(i, j int) {
if i != j {
i, j = d.find(i), d.find(j)
if i != j {
d.inner[i] = j
d.counter--
}
}
}