Compute number of distinct values in an array.
Write a function
func Solution(A []int) int
that, given an array A consisting of N integers, returns the number of distinct values in array A.
For example, given array A consisting of six elements such that:
A[0] = 2 A[1] = 1 A[2] = 1 A[3] = 2 A[4] = 3 A[5] = 1 the function should return 3, because there are 3 distinct values appearing in array A, namely 1, 2 and 3.
Write an efficient algorithm for the following assumptions:
N is an integer within the range [0..100,000]; each element of array A is an integer within the range [−1,000,000..1,000,000]. Copyright 2009–2021 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
返回不重複的整數數量
- 方法ㄧ: 先排序, 在檢查當前跟前一個是不是同一個整數. 不是的會結果+1
- 方法二: 建立一個set. 最後返回set的長度
https://app.codility.com/programmers/lessons/6-sorting/distinct/
package Distinct
import "sort"
func Solution(A []int) int {
sort.Ints(A)
if len(A) == 0 {
return 0
}
result := 1
for i := 1; i < len(A); i++ {
if A[i] != A[i-1] {
result++
}
}
return result
}
func SolutionSet(A []int) int {
set := make(map[int]struct{})
var void struct{}
for i := 0; i < len(A); i++ {
if _, ok := set[A[i]]; !ok {
set[A[i]] = void
}
}
return len(set)
}