# 1. Check Positive or Negative
echo "Enter number:"
read n

if [ $n -ge 0 ]
then
    echo "Positive"
else
    echo "Negative"
fi


# 2. Swap Two Numbers Without Third Variable
echo "Enter first number:"
read a
echo "Enter second number:"
read b

a=$((a+b))
b=$((a-b))
a=$((a-b))

echo "After swap:"
echo "a=$a"
echo "b=$b"


# 3. Print Odd Numbers Up to N and Find Sum
echo "Enter N:"
read n

sum=0

for ((i=1;i<=n;i+=2))
do
    echo $i
    sum=$((sum+i))
done

echo "Sum = $sum"


# 4. Largest Among Three Numbers
echo "Enter three numbers:"
read a b c

if [ $a -ge $b ] && [ $a -ge $c ]
then
    echo "$a is largest"
elif [ $b -ge $a ] && [ $b -ge $c ]
then
    echo "$b is largest"
else
    echo "$c is largest"
fi


# 5. Prime Number Check
echo "Enter number:"
read n

flag=0

for ((i=2;i<n;i++))
do
    if [ $((n%i)) -eq 0 ]
    then
        flag=1
    fi
done

if [ $flag -eq 0 ]
then
    echo "Prime"
else
    echo "Not Prime"
fi


# 6. Factorial of a Number
echo "Enter number:"
read n

fact=1

for ((i=1;i<=n;i++))
do
    fact=$((fact*i))
done

echo "Factorial = $fact"


# 7. Reverse a Number
echo "Enter number:"
read n

rev=0

while [ $n -gt 0 ]
do
    rem=$((n%10))
    rev=$((rev*10+rem))
    n=$((n/10))
done

echo "Reverse = $rev"


# 8. Sum of Digits
echo "Enter number:"
read n

sum=0

while [ $n -gt 0 ]
do
    rem=$((n%10))
    sum=$((sum+rem))
    n=$((n/10))
done

echo "Sum = $sum"


# 9. Count Digits
echo "Enter number:"
read n

count=0

while [ $n -gt 0 ]
do
    count=$((count+1))
    n=$((n/10))
done

echo "Digits = $count"


# 10. Even or Odd
echo "Enter number:"
read n

if [ $((n%2)) -eq 0 ]
then
    echo "Even"
else
    echo "Odd"
fi


# 11. Palindrome Number
echo "Enter number:"
read n

temp=$n
rev=0

while [ $n -gt 0 ]
do
    rem=$((n%10))
    rev=$((rev*10+rem))
    n=$((n/10))
done

if [ $temp -eq $rev ]
then
    echo "Palindrome"
else
    echo "Not Palindrome"
fi


# 12. Multiplication Table
echo "Enter number:"
read n

for ((i=1;i<=10;i++))
do
    echo "$n x $i = $((n*i))"
done


# 13. Sum of First N Natural Numbers
echo "Enter N:"
read n

sum=0

for ((i=1;i<=n;i++))
do
    sum=$((sum+i))
done

echo "Sum = $sum"


# 14. Fibonacci Series
echo "Enter number of terms:"
read n

a=0
b=1

echo "$a"
echo "$b"

for ((i=2;i<n;i++))
do
    c=$((a+b))
    echo "$c"
    a=$b
    b=$c
done


# 15. Simple Calculator
echo "Enter two numbers:"
read a b

echo "1.Add 2.Subtract 3.Multiply 4.Divide"
read ch

case $ch in
1) echo "Sum = $((a+b))" ;;
2) echo "Sub = $((a-b))" ;;
3) echo "Mul = $((a*b))" ;;
4) echo "Div = $((a/b))" ;;
*) echo "Invalid choice"
esac


# 16. Count Files in Directory
count=$(ls | wc -l)

echo "Total files = $count"


# 17. Concatenate Two Strings
echo "Enter first string:"
read s1

echo "Enter second string:"
read s2

s3=$s1$s2

echo "Result = $s3"


# 18. Create File and Write Input
echo "Enter filename:"
read file

echo "Enter text:"
read text

echo $text > $file

echo "Written successfully"


# 19. Append Content to File
echo "Enter filename:"
read file

echo "Enter text to append:"
read text

echo $text >> $file

echo "Appended successfully"


# 20. Check Character Type
echo "Enter character:"
read ch

case $ch in
[A-Z]) echo "Uppercase" ;;
[a-z]) echo "Lowercase" ;;
[0-9]) echo "Digit" ;;
*) echo "Special Character" ;;
esac


# 21. Display First 5 Lines of File
echo "Enter filename:"
read file

head -5 $file


# 22. Sort Array in Ascending Order
arr=(5 2 8 1 3)

for ((i=0;i<5;i++))
do
    for ((j=i+1;j<5;j++))
    do
        if [ ${arr[i]} -gt ${arr[j]} ]
        then
            temp=${arr[i]}
            arr[i]=${arr[j]}
            arr[j]=$temp
        fi
    done
done

echo "${arr[@]}"


# 23. Second Largest Element
arr=(10 50 30 40 20)

largest=0
second=0

for i in ${arr[@]}
do
    if [ $i -gt $largest ]
    then
        second=$largest
        largest=$i
    elif [ $i -gt $second ]
    then
        second=$i
    fi
done

echo "Second Largest = $second"


# 24. Search Word in File
echo "Enter filename:"
read file

echo "Enter word:"
read word

grep "$word" $file


# 25. Remove Duplicate Elements
arr=(1 2 2 3 4 4 5)

echo "${arr[@]}" | tr ' ' '\n' | sort -u


# 26. Rename File
echo "Enter old filename:"
read old

echo "Enter new filename:"
read new

mv $old $new

echo "File renamed"


# 27. Frequency of Elements in Array
arr=(1 2 2 3 1 4 2)

for i in ${arr[@]}
do
    count=0
    for j in ${arr[@]}
    do
        if [ $i -eq $j ]
        then
            count=$((count+1))
        fi
    done
    echo "$i occurs $count times"
done


# 28. Length of String Without Built-in Function
echo "Enter string:"
read str

count=0

for ((i=0; ;i++))
do
    ch=${str:$i:1}

    if [ -z "$ch" ]
    then
        break
    fi

    count=$((count+1))
done

echo "Length = $count"


# 29. Compare Two Files
echo "Enter first file:"
read f1

echo "Enter second file:"
read f2

diff $f1 $f2


# 30. Count Lines Containing Specific Word
echo "Enter filename:"
read file

echo "Enter word:"
read word

count=$(grep -c "$word" $file)

echo "Lines containing word = $count"