exchange_2.m

tsp（旅行商问题） 利用matlab遗传算法、模拟退火算法以及lingo动态规划求解

function [d_f,pi_r]=exchange_2(pi0,d)
[m,n]=size(d);
clear m;
u=rand;
u=u*(n-2);
u=round(u);
if u<2
    u=2;
end
if u>n-2
    u=n-2;
end
v=rand;
v=v*(n-u+1);
v=round(v);
if v<1
    v=1;
end
v=u+v;
if v>n
    v=n;
end
pi_1(u)=pi0(v);
pi_1(v)=pi0(u);
if u>1
    for k=1:u-1
        pi_1(k)=pi0(k);
    end
end
if v>u+1
    for k=1:(v-u-1)
         pi_1(u+k)=pi0(v-k);
    end
end
if v<n
    for k=(v+1):n
        pi_1(k)=pi0(k);
    end
end
d_f=0;
if v<n
    d_f=d(pi0(u-1),pi0(v))+d(pi0(u),pi0(v+1));
    for k=(u+1):n
        d_f=d_f+d(pi0(k),pi0(k-1));
    end
    d_f=d_f-d(pi0(u-1),pi0(u))-d(pi0(v),pi0(v+1));
    for k=(u+1):n
        d_f=d_f-d(pi0(k-1),pi0(k));
    end
else
    d_f=d(pi0(u-1),pi0(v))+d(pi0(u),pi0(1))-d(pi0(u-1),pi0(u))-d(pi0(v),pi0(1));
    for k=(u+1):n
        d_f=d_f+d(pi0(k),pi0(k-1));
    end
    for k=(u+1):n
        d_f=d_f-d(pi0(k-1),pi0(k));
    end
end
pi_r=pi_1;