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Write a Golang program to find duplicate elements in a given range
We can solve this problem in two different ways. Let’s check the first method.
Method 1:
Examples
Input Array = [1, 2, 3, 4, 4] => Range is from 1 to 5 but 4 is a duplicate element in this range.
Approach to solve this problem
- Step 1: Define a method that accepts an array.
- Step 2: Declare a visited map.
- Step 3: Iterate the given array. If the element exists in the visited map, then return that element.
- Step 4: Else, return -1.
Program
package main
import "fmt"
func duplicateInArray(arr []int) int{
visited := make(map[int]bool, 0)
for i:=0; i<len(arr); i++{
if visited[arr[i]] == true{
return arr[i]
} else {
visited[arr[i]] = true
}
}
return -1
}
func main(){
fmt.Println(duplicateInArray([]int{1, 2, 3, 4, 4}))
fmt.Println(duplicateInArray([]int{4, 5, 6, 7, 7}))
fmt.Println(duplicateInArray([]int{1, 2, 3, 4, 5}))
}Output
4 7 -1
Now, let’s check the second method to solve this problem.
Method 2: Using XOR operation
Examples
Input Array = [1, 2, 3, 4, 4] => Range is from 1 to 5 but 4 is duplicate in that range.
Range is from 1 to 5. => XOR => 0^1^2^3^4^4^0^1^2^3^4 => 4 (since 0^1=1).
Approach to solve this problem
- Step 1: Define a method that accepts an array.
- Step 2: Find the range value from the given array and define a variable xor, initialize with 0.
- Step 3: Iterate the given array and do a xor operation with the array’s elements.
- Step 4: Also perform xor operation from the lower range value to the higher range value.
- Step 5: At the end, return the xor variable, non-zero value for duplicate element.
Program
package main
import "fmt"
func duplicateInArray(arr []int, r int) int{
xor := 0
for i:=0; i<len(arr); i++{
xor ^= arr[i]
}
for j:=1; j<=r-1; j++{
xor ^= j
}
return xor
}Output
4 3 1 0
Updated on: 04-Feb-2021
472 Views
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