在列表中查找最大值 - Prolog
问题描述：
我刚刚被介绍到 Prolog，我正在尝试编写一个谓词来查找整数列表的最大值.我需要写一个从头开始比较，另一个从结尾比较.到目前为止，我已经:
I was just introduced to Prolog and am trying to write a predicate that finds the Max value of a list of integers. I need to write one that compares from the beginning and the other that compares from the end. So far, I have:
max2([],R).
max2([X|Xs], R):- X > R, max2(Xs, X).
max2([X|Xs], R):- X <= R, max2(Xs, R).
我意识到R尚未启动，因此无法进行比较.我是否需要 3 个参数才能完成此操作?
I realize that R hasn't been initiated yet, so it's unable to make the comparison. Do i need 3 arguments in order to complete this?
答
my_max([], R, R). %end
my_max([X|Xs], WK, R):- X > WK, my_max(Xs, X, R). %WK is Carry about
my_max([X|Xs], WK, R):- X =< WK, my_max(Xs, WK, R).
my_max([X|Xs], R):- my_max(Xs, X, R). %start
其他方式
%max of list
max_l([X],X) :- !, true.
%max_l([X],X). %unuse cut
%max_l([X],X):- false.
max_l([X|Xs], M):- max_l(Xs, M), M >= X.
max_l([X|Xs], X):- max_l(Xs, M), X > M.