The JSON parsing is forgivable (I actually didn't know that scanf computed the length of the string for every call) but the deduplication code is a lot less so,

The JSON parsing is forgivable (I actually didn't know that scanf computed the length of the string for every call) but the deduplication code is a lot less so, especially in C++ where maps are available in the STL. It also comforts me into my decision of never using scanf, instead preferring manual parsing with strtok_r and strtol and friends. It's just not robust and flexible enough.