Even checking the right condition Go throwing, panic: runtime error: index out of range [3] with length 3

Question

package main

import "fmt"

func mergeSortedArray(arr1 []int, arr2 []int) []int {

    var mergedArr []int
    lengthArr := len(arr1) + len(arr2)
    fmt.Println(lengthArr)

    i := 0
    j := 0
    //Check input
    if len(arr1) == 0 {
        return arr2
    }

    if len(arr2) == 0 {
        return arr1
    }

    for c := 0; c < lengthArr; c++ {
        if arr1[i] >= arr2[j] {
            mergedArr = append(mergedArr, arr2[j])
            j++
        } else {
            mergedArr = append(mergedArr, arr1[i])
            i++
        }
    }
    return mergedArr

}

func main() {

    arr1 := []int{0, 3, 31}
    arr2 := []int{4, 6, 30}

    m := mergeSortedArray(arr1, arr2)
    fmt.Println(m)
    //Exp output : 0,3,4,6,30,31
}

Important catch, while doing below operation for c := 0; c < lengthArr-1; c++

it is giving result : 0,3,4,6,30.

Can anyone look into this code, it will be a great help. Thanks in advance.

Answer 1

There is a problem with your algorithm, you are assuming your arrays are equally distributed.

You need to check if you already added all entries from one array then add the rest of the second one

func mergeSortedArray(arr1 []int, arr2 []int) []int {
    var mergedArr []int
    lengthArr := len(arr1) + len(arr2)
    fmt.Println(lengthArr)

    i := 0
    j := 0
    //Check input
    if len(arr1) == 0 {
        return arr2
    }

    if len(arr2) == 0 {
        return arr1
    }

    for c := 0; c < lengthArr; c++ {
        if i >= len(arr1) {
            mergedArr = append(mergedArr, arr2[j:len(arr2)]...)
            break
        } else if j >= len(arr2) {
            mergedArr = append(mergedArr, arr1[i:len(arr1)]...)
            break
        } else if arr1[i] >= arr2[j] {
            mergedArr = append(mergedArr, arr2[j])
            j++
        } else {
            mergedArr = append(mergedArr, arr1[i])
            i++
        }
    }
    return mergedArr

}