Lower bound with comparision

#1

when we are passing compare function in lower bound with <= function then why we are subtracting 1 in getting the desired index
for example in indian money change video
lb = lower_bound(coins, coins+n, money, compare) - coins - 1 ;
why we need -1 when we are already passed compare function as less than or equal to

#2

Hey @code_beater
In our custom implementation of compare function, it’ll always return index of first value greater than X. So if you have array = { 1, 2, 4, 7 } and you search for X = 4 or 5 it’ll return index of 7 itself. So you subtract -1 to get index of first value <= X which is index of 4 in our case.

If your doubt is resolved please mark it as cleared.

#3

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