Problem : Magical Jungle
There is a category of problem which tend to overwhelm you with the amount logical complexity it brings in. But when you come across its solution, it simply amazes you with its simplicity. This is one such puzzle! Let's go through the solution:
Simply ignore the number "72 lions". This has been given just to make the problem look complicated. It's also clear that, it is almost impossible to think on the scale of 72 lions, hence let's try to grow the problem with very small number of lions.
CASE 1: One lion and one sheep
This is a trivial case and the lion will simple eat the sheep, with no fear of being converted in the sheep since there is no more lion to kill it later.
CASE 2: Two lion and one sheep
Any lion would think that if it eats the sheep, it will be converted into a sheep and second lion would take no time to eat it. Since the problem has already stated that lions are intelligent and though they have no hesitation in being converted to a sheep but in no situation they would prefer to be eaten by another lion. Hence in this combination, no lion would dare to eat the sheep to avoid the inevitable consequence, and sheep would enjoy the safe stay.
CASE 3: Three lion and one sheep
Any lion would think that if it eats the sheep, it will be converted into the same and the remaining population of the community would be one sheep and two lion. We have already discussed the scenario of 2 lions and 1 sheep and concluded that it's a stable combination, no one eats no body.
Since the lion is intelligent, it will soon realize that it's fairly safe to eat the sheep, since after that, the problem will reduce to case 2, and it will be in a safe haven spending rest of it's life as sheep.
On the similar pattern you can extrapolate the situation with more and more number of lions and try to find a pattern. But thankfully it is not needed since we already have hit a pattern, and are in a situation to conclude.
Whenever the number of lion would be an even number sheep would be safe and whenever the number of lion would be an odd number the sheep will be eaten immediately, however there will be no subsequent kill because the number of lions would reduce to even.
Since in our problem total number of lion is 72, which happens to be an even number, hence no sheep would be eaten and it would survive without realizing the beautiful logic which is protecting it.