minimum no of swap of operator to compliment expression tree evaluation : we have a expression tree where leaf node contain 0 or 1 as value, and all the internal nodes contain "&" or "||" as operator.now we evaluate the tree the result will be either 0 or 1.
The question is minimum no of swap of internal node required to compliment the result of original expression tree.
we can flip any internal node e.g:if it is a "&" we can make it "||" and vice versa.

To solve this I tried the following technique but I didn't succeeded in it:
my approach was that I would check the root whether it is a "&" or "||" operator and what was the result of evaluation tree 0 or 1.depending on that we go forward.