improve day 5 by using a map

d05.go

@@ -13,24 +13,21 @@ type maprange struct {
     dst uint64
 } 
 
-type mapdir struct {
-	src string
-	dst string
-}
-
 type mapval struct {
     cunt uint64
     rnge maprange
 }
 
 type mapping struct {
-    dir mapdir
+    src string
+    dst string
     val []mapval
 }
 
-func parse(f *os.File) (seeds []uint64, maps []mapping) {
+func parse(f *os.File) (seeds []uint64, maps map[string]mapping) {
     s := bufio.NewScanner(f)
 
+    maps = make(map[string]mapping)
     inmap := false
     var curmap mapping
     for s.Scan() {
@@ -44,7 +41,7 @@ func parse(f *os.File) (seeds []uint64, maps []mapping) {
             }
 
         case strings.HasSuffix(line, " map:"):
-            if inmap { maps = append(maps, curmap) }
+            if inmap { maps[curmap.src] = curmap }
             curmap = mapping{}
             inmap = true
 
@@ -52,8 +49,8 @@ func parse(f *os.File) (seeds []uint64, maps []mapping) {
             split2 := strings.Index(line, " ")
             src := line[:split1]
             dst := line[split1 + 4:split2]
-            curmap.dir.src = src
-            curmap.dir.dst = dst
+            curmap.src = src
+            curmap.dst = dst
 
         case strings.Count(line, " ") >= 2 && inmap:
             thing := strings.Split(line, " ")
@@ -64,28 +61,19 @@ func parse(f *os.File) (seeds []uint64, maps []mapping) {
             curmap.val = append(curmap.val, val)
         }
     }
-    if inmap { maps = append(maps, curmap) }
+    if inmap { maps[curmap.src] = curmap }
 
     return
 }
 
-func part1(init_seeds []uint64, maps []mapping) uint64 {
+func part1(init_seeds []uint64, maps map[string]mapping) uint64 {
     seeds := append(make([]uint64, 0, len(init_seeds)), init_seeds...)
 
     currency := "seed"
     for currency != "location" {
-        var map_cur mapping
-        map_found := false
-        for _, v := range maps {
-            if v.dir.src == currency {
-                map_cur = v
-                map_found = true
-                break
-            }
-        }
-        if !map_found { break }
+        map_cur := maps[currency]
+        currency = map_cur.dst
 
-        currency = map_cur.dir.dst
         for i, v := range seeds {
             for _, x := range map_cur.val {
                 tmp := v - x.rnge.src
@@ -105,7 +93,7 @@ func part1(init_seeds []uint64, maps []mapping) uint64 {
     return min
 }
 
-func part2(init_seeds []uint64, maps []mapping) uint64 {
+func part2(init_seeds []uint64, maps map[string]mapping) uint64 {
     seeds := make([]maprange, 0)
     for i, _ := range init_seeds {
         if i % 2 == 1 { continue }
@@ -117,18 +105,9 @@ func part2(init_seeds []uint64, maps []mapping) uint64 {
 
     currency := "seed"
     for currency != "location" {
-        var map_cur mapping
-        map_found := false
-        for _, v := range maps {
-            if v.dir.src == currency {
-                map_cur = v
-                map_found = true
-                break
-            }
-        }
-        if !map_found { break }
+        map_cur := maps[currency]
+        currency = map_cur.dst
 
-        currency = map_cur.dir.dst
         newseedrnge := make([]maprange, 0)
         for _, v := range seeds {
             for _, x := range map_cur.val {
@@ -160,11 +139,11 @@ func part2(init_seeds []uint64, maps []mapping) uint64 {
         seeds = newseedrnge
     }
 
-    minrnge := seeds[0].src
+    min := seeds[0].src
     for _, v := range seeds[1:] {
-        if v.src < minrnge { minrnge = v.src }
+        if v.src < min { min = v.src }
     }
-    return minrnge
+    return min
 }
 
 func main() {