Why are we using the statement : lower_bound(arr,arr+n,key,compare) -1 ? Why are we subtracting 1?
Why are we subtracting 1 from the result?
@HemantKumar hey normally lower bound hme finding key ke equal ya usse bda index deta hai but hme ek kam chyy use kyunki hme chota dhundna hai so -1 kia hai.
If u observe that
if u just write
lower_bound(arr,arr+n,key,compare)
without -1 then giving a money value which exists in the aray
would return a wrong value
it returns the next greater value in the array
hence the -1 is required so that even 120 and 100 would give us answer 100
in case -1 is not written then 100 would give answer 200 because of the comparator
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