I'm working on UVa #112 Tree Summing. I have what I think should be a working solution but it is not accepted by the online judge due to a basic misunderstanding of the problem on my part. Consider the following inputs: -1 (-1()()) 77 (77(1()())()) or diagrammatically, the trees look like: -1 77 / \ / \ () () 1 () / \ () () According to at least two working solutions, the correct output for the above inputs is: yes no However, I don't understand why the second one should be 'no'. It looks to me like the rightmost path of the tree should give the proper sum. What am I missing?