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sourceHead -> "A" -> "B" -> "C" -> NULL
your pointer ^
targetHead -> NULL
sourceHead -> "A" -> "B" -> "C" -> NULL
your pointer ^
targetHead -> "A" -> NULL
sourceHead -> "A" -> "B" -> "C" -> NULL
your pointer ^
targetHead -> "B" -> "A" -> NULL
sourceHead -> "A" -> "B" -> "C" -> NULL
your pointer ^
targetHead -> "C" -> "B" -> "A" -> NULL