use bit_array instead of []bool

src/main.odin

@@ -1,5 +1,6 @@
 package main
 
+import "core:container/bit_array"
 import "core:fmt"
 import "core:math"
 import "core:os"
@@ -28,7 +29,7 @@ read_data :: proc(file: string) -> (res: [NUMBER_OF_ITEMS]Item, ok := true) {
 	return
 }
 
-Chromosome :: [NUMBER_OF_ITEMS]bool
+Chromosome :: bit_array.Bit_Array
 
 distance :: proc(x, y: int) -> int {
 	return math.abs(x - y)
@@ -39,10 +40,10 @@ penalize :: proc(d: int) -> int {
 }
 
 // side-effect: reads global `items`
-fitness :: proc(chrom: Chromosome) -> int {
+fitness :: proc(chrom: ^Chromosome) -> int {
 	tot_profit, tot_weight := 0, 0
-	for bit, idx in chrom {
-		if !bit {continue}
+	for idx in 0 ..< bit_array.len(chrom) {
+		if !bit_array.get(chrom, idx) {continue} 	// nb: eliminating branch may be faster
 		tot_profit += items[idx].profit
 		tot_weight += items[idx].weight
 	}