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How to Swap First and Last Elements in List Using Python – GATE, Interview & Placement Practice
Jun 1, 2025
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uh hello guys welcome to this video so
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in this video I'll show you a very
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common question which is asked inside
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Python programs interviews and
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competitive exams and placements so how
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to swap the first and the last element
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in the array or list so if you have a
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list of numbers so in this case I have a
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list of numbers 10 20 30 40 50 so now I
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have the very first element which is 10
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right here the very last element which
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is 50 so what if I want to exchange or
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swap these two numbers so such that 50
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should be replaced here and 10 will be
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replaced here so there is uh not a
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built-in function in Python that you
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want to do this so we actually use the
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concept of negative indexing negative
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indexing in Python simply means that
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negative indexing like this minus one so
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minus one if you write in Python it
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refers to the rightmost element in the
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array as you can see so if I just show
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you right
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here if I print out let's suppose
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uh this is our list and if I say
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negative
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-1 so in other programming languages
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such as C C++ JavaScript this negative
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index is invalid but in Python if you
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write uh array followed by -1 this will
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refer to the rightmost element and then
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this will be -2 this will be -3 -4 -5 so
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if I just print it out let's suppose if
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I run the program right here python app
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9 pi you will see as soon as I write
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negative -1 so rightmost element is
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printed out here you can see 50 is
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printed out if I say here -2 if I change
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this say -2 you will see it will now
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print out
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40 so with this negative indexing
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concept we can easily exchange the first
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and the last element very easily so what
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we are doing right here we are easily
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using the third variable
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temporary you can call this anything we
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are using the temp variable we are
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storing this the very first element
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which is 10 right here in this variable
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so temp is equal to 10
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and then we are using the negative
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indexing right here to get the rightmost
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element and we are storing it to the
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first index which is zero so we are
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transferring this value 50 to
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10 and then we store the value which is
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stored inside temp which is 10 to
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the rightmost element again we can
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access it by minus1 so we are simply
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saying temp this is a threeline logic so
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it is also used to swap two numbers but
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we are using it to swap the first and
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the last element essentially I just
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wanted to tell you about the concept of
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negative indexing which is exist so if
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you execute this program now just
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execute this you will see original list
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was 10 20 30 40 50 now after swapping
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the first and the last element we
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actually 50 is there as the first
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element and 10 has referred to the last
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so in this easy way you can explain
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inside the interview the concept of
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negative indexing and it becomes really
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easy to swap the first and the last
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element in the list or array and also
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check out my website guys
3:30
freemediatools.com
3:32
uh which contains thousands of tools
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