1. A method of converting first data into second data, comprising: determining a target symbol corresponding to the first data by utilizing a determining unit adaptively according to occurrence probability of candidate syntax element values of a syntax element referring to a probability table which stores occurrence probability indication values for all syntax element values, wherein the first data is the syntax element and the occurrence probability indication values are integer; wherein determining the target symbol corresponding to the first data comprises: providing a mapping table which stores mapping between all candidate syntax element values of the syntax element and a plurality of candidate symbols; searching the mapping table for the target symbol corresponding to a syntax element value of the syntax element; and generating an updated probability table by updating the probability table, wherein comprising: adjusting an occurrence probability indication value stored in a first table entry indexed by a first index value corresponding to the syntax element value of the syntax element; and selectively updating the mapping table according to the updated probability table, wherein when an occurrence probability order of occurrence probability indication values stored in sequential table entries of the updated probability table is not a sequential order, swapping the adjusted occurrence probability indication value stored in the first table entry of the updated probability table that is indexed by the first index value and an occurrence probability indication value stored in a second table entry of the updated probability table that is indexed by a second index value, and swapping a syntax element value stored in a first table entry of the mapping table that is indexed by the first index value and a syntax element value stored in a second table entry of the mapping table that is indexed by the second index value, when the adjusted occurrence probability indication value stored in the first table entry of the updated probability table reaches a predetermined threshold, decreasing occurrence probability indication values stored in all table entries of the updated probability table; and generating the second data corresponding to the determined target symbol, wherein the second data is an entropy-coded result of the syntax element.