非对称TSP问题matlab

以下是解决非对称TSP问题的Matlab脚本示例：

% 读取问题文件
filename = 'filename.tsp';
[coords, numpoints, name] = readCoords(filename);

% 计算距离矩阵
distmat = zeros(numpoints, numpoints);
for i = 1:numpoints
    for j = i+1:numpoints
        distmat(i,j) = sqrt(sum((coords(i,:) - coords(j,:)).^2));
        distmat(j,i) = distmat(i,j);
    end
end

% 定义参数
numants = 10; % 蚂蚁数量
numiter = 100; % 迭代次数
alpha = 1; % 信息素重要程度因子
beta = 5; % 启发式因子
rho = 0.5; % 信息素挥发因子
q = 1; % 信息素增加强度因子

% 初始化信息素矩阵
pheromone = ones(numpoints, numpoints);

% 迭代求解
bestpath = zeros(numiter, numpoints);
for iter = 1:numiter
    % 初始化蚂蚁位置
    curloc = zeros(numants, 1);
    for ant = 1:numants
        curloc(ant) = randi(numpoints);
    end
    
    % 蚂蚁移动
    for step = 2:numpoints
        for ant = 1:numants
            % 计算可行解集合
            visited = curloc(ant, 1:step-1);
            unvisited = setdiff(1:numpoints, visited);
            feasible = zeros(1, length(unvisited));
            for i = 1:length(unvisited)
                feasible(i) = distmat(visited(end), unvisited(i));
            end
            
            % 计算转移概率
            prob = zeros(1, length(unvisited));
            for i = 1:length(unvisited)
                prob(i) = pheromone(visited(end), unvisited(i))^alpha * (1./feasible(i))^beta;
            end
            prob = prob / sum(prob);
            
            % 选择下一个节点
            nextloc = randsample(unvisited, 1, true, prob);
            curloc(ant, step) = nextloc;
        end
    end
    
    % 计算路径长度
    pathlen = zeros(numants, 1);
    for ant = 1:numants
        for i = 1:numpoints-1
            pathlen(ant) = pathlen(ant) + distmat(curloc(ant,i), curloc(ant,i+1));
        end
        pathlen(ant) = pathlen(ant) + distmat(curloc(ant,end), curloc(ant,1));
    end
    
    % 更新信息素
    delta_pheromone = zeros(numpoints, numpoints);
    for ant = 1:numants
        for i = 1:numpoints-1
            delta_pheromone(curloc(ant,i), curloc(ant,i+1)) = delta_pheromone(curloc(ant,i), curloc(ant,i+1)) + q/pathlen(ant);
            delta_pheromone(curloc(ant,i+1), curloc(ant,i)) = delta_pheromone(curloc(ant,i+1), curloc(ant,i)) + q/pathlen(ant);
        end
        delta_pheromone(curloc(ant,end), curloc(ant,1)) = delta_pheromone(curloc(ant,end), curloc(ant,1)) + q/pathlen(ant);
        delta_pheromone(curloc(ant,1), curloc(ant,end)) = delta_pheromone(curloc(ant,1), curloc(ant,end)) + q/pathlen(ant);
    end
    pheromone = (1-rho)*pheromone + delta_pheromone;
    
    % 记录最优路径
    [~, idx] = min(pathlen);
    bestpath(iter,:) = curloc(idx,:);
end

% 输出结果
bestlen = inf;
for i = 1:numiter
    len = 0;
    for j = 1:numpoints-1
        len = len + distmat(bestpath(i,j), bestpath(i,j+1));
    end
    len = len + distmat(bestpath(i,end), bestpath(i,1));
    if len < bestlen
        bestlen = len;
        besttour = bestpath(i,:);
    end
end
fprintf('最优路径长度为：%f\n', bestlen);
fprintf('最优路径为：');
for i = 1:numpoints
    fprintf('%d ', besttour(i));
end
fprintf('\n');