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[Golang] Set Difference of Two Arrays
source link: http://siongui.github.io/2018/03/14/go-set-difference-of-two-arrays/
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[Golang] Set Difference of Two Arrays
March 14, 2018
Find the elements in one array but not in the other, i.e., set difference of two arrays. In mathematical term:
A − B = {x ∈ A and x ∉ B}
The idea is to convert the array B to the data structure of key-value pairs, i.e., hash table. The hash table in Go is built-in map type. Then we check if items in array A is in the hash table. If not, append the item to the difference array, and return the difference array after finish.
The following is the implementation of above idea.
package main
import (
"fmt"
)
// Set Difference: A - B
func Difference(a, b []int) (diff []int) {
m := make(map[int]bool)
for _, item := range b {
m[item] = true
}
for _, item := range a {
if _, ok := m[item]; !ok {
diff = append(diff, item)
}
}
return
}
func main() {
var a = []int{1, 2, 3, 4, 5}
var b = []int{2, 3, 5, 7, 11}
fmt.Println(Difference(a, b))
}
The result will be [1 4].
Tested on: Go Playground
References:
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