Question

How to generate N random integers, each with distinct digits and exact length L in Go

Answer 1

package main

import (
    "fmt"
    "math/rand"
    "time"
)

// hasDistinctDigits checks whether all digits in the number are unique.
func hasDistinctDigits(num int, length int) bool {
    seen := make(map[rune]bool)
    s := fmt.Sprintf("%0*d", length, num) // pad with leading zeros if needed

    for _, ch := range s {
        if seen[ch] {
            return false
        }
        seen[ch] = true
    }
    return true
}

// generateDistinctDigitNumbers generates N integers of exact length L,
// each containing only distinct digits.
func generateDistinctDigitNumbers(N int, L int) []int {
    rand.Seed(time.Now().UnixNano())

    results := make([]int, 0, N)
    min := intPow(10, L-1)
    max := intPow(10, L) - 1

    for len(results) < N {
        candidate := rand.Intn(max-min+1) + min

        if hasDistinctDigits(candidate, L) {
            results = append(results, candidate)
        }
    }

    return results
}

// intPow computes integer powers.
func intPow(base, exp int) int {
    result := 1
    for i := 0; i < exp; i++ {
        result *= base
    }
    return result
}

func main() {
    N := 10
    L := 6

    numbers := generateDistinctDigitNumbers(N, L)
    fmt.Println("Generated numbers:", numbers)
}



/*
run:

Generated numbers: [308726 243708 742391 293470 183904 230415 983705 947352 421650 906748]

*/

 

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