Overview
An array is given in which all elements are in the range [1, n] where n is the length of the array. The objective is to find all duplicates in that given array
Examples
Input: [1, 2, 3, 2, 4, 3]
Output: [2, 3]The idea here is to take advantage of the fact that numbers are in the range [1, n]. For every element in the array, increase the value at its index by n. So
- For getting a value at an index we value%n
- In the end, if the value at any index is greater than 2*n then it is duplicated.
Program
Here is the program for the same.
package main
import "fmt"
func findDuplicates(nums []int) []int {
lenNums := len(nums)
for i := 0; i < lenNums; i++ {
index := (nums[i] - 1) % lenNums
nums[index] = lenNums + nums[index]
}
k := 0
for i := 0; i < lenNums; i++ {
if nums[i] > 2*lenNums {
nums[k] = i + 1
k++
}
}
return nums[0:k]
}
func main() {
output := findDuplicates([]int{1, 2, 3, 2, 4, 3})
fmt.Println(output)
}Output
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