counter([],[]).
counter([H|T],[[H,C1]|R]) :- counter(T,[[H,C]|R]),!, C1 is C+1.
counter([H|T],[[H,1]|R]) :- counter(T,R).
"!"的影响是什么？因为我在上面和下面的代码中输入相同的输出？
counter([],[]).
counter([H|T],[[H,C1]|R]) :- counter(T,[[H,C]|R]),C1 is C+1.
counter([H|T],[[H,1]|R]) :- counter(T,R).
我是Prolog的新手.