alazyreader/AdventOfCode2021
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speed up day 5 with preallocated slices, not a map

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This commit is contained in:
David 2021-12-05 13:24:59 -05:00
parent c5dbac0e9c
commit 019b87c43c
1 changed files with 15 additions and 8 deletions
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23
05/main.go
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@ -42,12 +42,15 @@ type point struct {
} }
type grid struct { type grid struct {
m map[point]int m [][]int
} }
func (g *grid) AddLine(start, end point, includeHorizontal bool) { func (g *grid) AddLine(start, end point, includeHorizontal bool) {
for _, p := range LineFromPoints(start, end, includeHorizontal) { for _, p := range LineFromPoints(start, end, includeHorizontal) {
g.m[p]++ if g.m[p.x] == nil {
g.m[p.x] = make([]int, 1000)
}
g.m[p.x][p.y]++
} }
} }
@ -109,7 +112,7 @@ func partOne() {
scanner := makeScanner(false) scanner := makeScanner(false)
grid := &grid{ grid := &grid{
m: map[point]int{}, m: make([][]int, 1000),
} }
for scanner.Scan() { for scanner.Scan() {
line := scanner.Text() line := scanner.Text()
@ -118,8 +121,10 @@ func partOne() {
} }
var danger int var danger int
for i := range grid.m { for i := range grid.m {
if grid.m[i] > 1 { for j := range grid.m[i] {
danger++ if grid.m[i][j] > 1 {
danger++
}
} }
} }
fmt.Println(danger) fmt.Println(danger)
@ -129,7 +134,7 @@ func partTwo() {
scanner := makeScanner(false) scanner := makeScanner(false)
grid := &grid{ grid := &grid{
m: map[point]int{}, m: make([][]int, 1000),
} }
for scanner.Scan() { for scanner.Scan() {
line := scanner.Text() line := scanner.Text()
@ -138,8 +143,10 @@ func partTwo() {
} }
var danger int var danger int
for i := range grid.m { for i := range grid.m {
if grid.m[i] > 1 { for j := range grid.m[i] {
danger++ if grid.m[i][j] > 1 {
danger++
}
} }
} }
fmt.Println(danger) fmt.Println(danger)