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How to Get Random Permutation of Integers in Golang?

• Last Updated : 26 Mar, 2020

Go language provides inbuilt support for generating random numbers of the specified type with the help of a math/rand package. This package implements pseudo-random number generators. These random numbers are generated by a source and this source produces a deterministic sequence of values whenever the program run. And if you want to random numbers for security-sensitive work, then use the crypto/rand package.

You are allowed to generate a slice of n ints which contains a non-negative pseudo-random permutation of the integers [0, n) from the default source with the help of the Perm() Function provided by the math/rand package. So, you need to add a math/rand package in your program with the help of the import keyword to access the Perm() function.

Syntax:

`func Perm(n int) []int`

Let us discuss this concept with the help of the given examples:

Example 1:

 `// Golang program to illustrate``// how to get a random number``package main`` ` `import (``    ``"fmt"``    ``"math/rand"``)`` ` `// Main function``func main() {`` ` `    ``// Getting the random permutation``    ``// of integers in the form of slice``    ``// Using Perm() function``    ``for` `_, res_1 := range ``rand``.Perm(4) {`` ` `        ``// Displaying the result``        ``fmt.Println(``"Slice 1 Element: "``, res_1)``    ``}``    ``for` `_, res_2 := range ``rand``.Perm(3) {`` ` `        ``// Displaying the result``        ``fmt.Println(``"Slice 2 Element: "``, res_2)``    ``}`` ` `}`

Output:

```Slice 1 Element:  0
Slice 1 Element:  1
Slice 1 Element:  2
Slice 1 Element:  3
Slice 2 Element:  1
Slice 2 Element:  2
Slice 2 Element:  0
```

Example 2:

 `// Golang program to illustrate``// how to get a random permutation``// of integers``package main`` ` `import (``    ``"fmt"``    ``"math/rand"``)`` ` `// Main function``func main() {`` ` `    ``// Getting the random permutation``    ``// of integers in the form of slice``    ``// Using Perm() function``    ``res_1 := ``rand``.Perm(5)``    ``res_2 := ``rand``.Perm(7)``    ``fmt.Println(``"Slice 1: "``, res_1)`` ` `    ``// Finding the length of the slice``    ``fmt.Println(``"Length of Slice 1: "``, len(res_1))`` ` `    ``// Finding the capacity of the slice``    ``fmt.Println(``"Capacity of Slice 1: "``, cap(res_1))`` ` `    ``fmt.Println(``"Slice 2: "``, res_2)`` ` `    ``// Finding the length of the slice``    ``fmt.Println(``"Length of Slice 2: "``, len(res_2))`` ` `    ``// Finding the capacity of the slice``    ``fmt.Println(``"Capacity of Slice 2: "``, cap(res_2))`` ` `}`

Output:

```Slice 1:  [0 4 2 3 1]
Length of Slice 1:  5
Capacity of Slice 1:  5
Slice 2:  [4 1 5 0 3 2 6]
Length of Slice 2:  7
Capacity of Slice 2:  7
```

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