Consider a Array of N-1 elements which has values from 1 to N which means one of the element is always missing. So, In this Blog, sharing the code for the same.

For Example a=( 4 3 2 5) , here number of elements is N-1 which means 4 and values ranges from 1 to N(which means 5) and hence *we need to print that missing element or number is 1*.

`arr=(4 3 2 5) ## Array of 4 elements(N-1)`

len_arr_1=$(( ${#arr[@]} +1)) ##Making length equal to N (5)

len_arr=${#arr[@]} ## Traversing all elements of an Array

i=1

k=0

while [ $i -le $len_arr_1 ]

do

j=0

while [ $j -lt $len_arr ]

do

if [ $i -eq ${arr[j]} ]

then

echo $i " is present"

k=$i ## This assignment will help to identify which element or number is not present

break

fi

j=$(( $j + 1))

done

if [ $k -ne $i ] ##Checking which number is not present

then

echo $i " is not present"

fi

i=$(( $i + 1))

done