model:sets:cities/1..9/:level;link(cities, cities): distance, x;   !距离矩阵;endsetsdata:distance = 0    200   660   170   127   225   490  420   330                                     200    0    820   300   90    60    310  225   151                                 660    820    0    530   770   120   1110 1050  960                             170    300    530    0    280   350   600  550   450                         127    90    770    280    0    110   370  310   210                       225    60    120    350    110    0    280  250   120                   490    310    1110    600    370    280    0    290   190               420    225    1050    550    310    250    290    0    160           330    151    960    450    210    120    190    160    0 ;enddatan = @size(cities);!目标函数;min=@sum(link:distance * x);@For(cities(k):     !进入城市k;     @sum(cities(i) | i #ne# k: x(i,k)) = 1;     !离开城市k;     @sum(cities(j) | j #ne# k: x(k,j)) = 1;    );    !保证不出现子圈;    @for(cities(i) | i #gt# 1:    @for(cities(j) | j #gt# 1 #and# i#ne#j:        level(i)-level(j) + n*x(i,j) <= n-1);     );        !限制u的范围以加速模型的求解，保证所加限制并不排除掉TSP问题的最优解;    @for(cities(i) | i #gt# 1: level(i) <= n-2);    !定义x为 0\1变量;    @for(link:@bin(x));end