Google Interview Question for Java Developers

Country: United States

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we are given a string as input.
the SWAP rules are:
(*) the 'L' character can only swap to the left, i.e. move left.
(*) the 'R' character can only swap to the right, i.e. move right.
both 'L' & 'R' can only swap with the '_' character.
so we need to find a sequence of SWAPs that will bring the left-most character can arrive at the right-most position
i'm assuming the string is made of only those 3 characters bcz otherwise, a different character at either ends means it can SWAP.
and in any other position, its simply ignored bcz it cannot SWAP.

!!! Observation !!!
* it seems that once we have 'L' on right-most position, 'R' on left-most position (to satisfy initial requirement), we only need 2 '_' characters within the string, regardless of their position.
lets all these two '_' characters F & S *for first & second from left.
so the following sequence always works:
SWAP(left-most index <--> S)
SWAP(right-most index <--> F)
SWAP(right-most index <--> original position of S)

- January 20, 2018 | Flag Reply

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