Decrease array length
I am trying to concatenate two string arrays into one. The resulting array should remove all duplicate elements.
func MergeArrays(str1, str2 []string) []string {
c := make([]string, len(str1)+len(str2), cap(str1)+cap(str2))
k := make(map[string]bool)
for i, s := range str1 {
if _, ok := k[s]; !ok {
c[i] = s
k[s] = true
}
}
for j, s := range str2 {
if _, ok := k[s]; !ok {
c[j+len(str1)] = s
k[s] = true
}
}
return c
}
Test data
str1 := []string{"a", "b"}
str2 := []string{"c", "d", "a"}
Output:
"a", "b", "c", "d"
length of the array "5"
I get the output that I want, but the length of the array should be 4
, not 5
. I can understand why it prints 5
, but I need an output array of length 4
. Is there any other way to merge two arrays.
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Start with a length of zero and add it when adding an item. For example,
package main
import "fmt"
func MergeArrays(a1, a2 []string) []string {
m := make([]string, 0, len(a1)+len(a2))
k := make(map[string]bool, len(a1)+len(a2))
for _, aa := range [][]string{a1, a2} {
for _, s := range aa {
if !k[s] {
m = append(m, s)
k[s] = true
}
}
}
return m
}
func main() {
a1 := []string{"a", "b"}
a2 := []string{"c", "d", "a"}
m := MergeArrays(a1, a2)
fmt.Println(len(m), m)
}
Output:
4 [a b c d]
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These are fragments, not arrays, and here is an example that solves your use case:
package main
import "fmt"
func MergeStringSlices(str1, str2 []string) []string {
m := make([]string, len(str1), len(str1)+len(str2))
copy(m, str1)
already_seen:
for _, s := range str2 {
for _, t := range m {
if s == t {
continue already_seen
}
}
m = append(m, s)
}
return m
}
func main() {
str1 := []string{"a", "b"}
str2 := []string{"c", "d", "a"}
fmt.Printf("%#v\n", MergeStringSlices(str1, str2))
}
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