以下是一个解决“不访问每个节点的CVRP”的示例代码：

import numpy as np
from ortools.constraint_solver import routing_enums_pb2
from ortools.constraint_solver import pywrapcp

def solve_cvrp_without_visiting_all_nodes(num_vehicles, num_nodes, vehicle_capacities, demands, distances):
    # 创建求解器
    routing = pywrapcp.RoutingModel(num_nodes, num_vehicles, 0)
    
    # 设置车辆容量限制
    def vehicle_capacity_callback(from_index):
        # 获取节点索引
        node_index = routing.IndexToNode(from_index)
        return vehicle_capacities[node_index]
    
    capacity_callback_index = routing.RegisterUnaryTransitCallback(vehicle_capacity_callback)
    routing.AddDimensionWithVehicleCapacity(capacity_callback_index, 0, vehicle_capacities, True, "Capacity")
    
    # 设置节点需求
    def demand_callback(from_index):
        # 获取节点索引
        node_index = routing.IndexToNode(from_index)
        return demands[node_index]
    
    demand_callback_index = routing.RegisterUnaryTransitCallback(demand_callback)
    routing.AddDimensionWithVehicleCapacity(demand_callback_index, 0, demands, True, "Demand")
    
    # 设置距离回调函数
    def distance_callback(from_index, to_index):
        # 获取节点索引
        from_node = routing.IndexToNode(from_index)
        to_node = routing.IndexToNode(to_index)
        return distances[from_node][to_node]
    
    transit_callback_index = routing.RegisterTransitCallback(distance_callback)
    routing.SetArcCostEvaluatorOfAllVehicles(transit_callback_index)
    
    # 设置每个车辆的起始节点
    for vehicle_id in range(num_vehicles):
        start_node = 0  # 起始节点为0
        routing.SetArcCostEvaluatorOfVehicle(transit_callback_index, vehicle_id, distance_callback)
        routing.AddDisjunction([start_node], 0)  # 不访问其他节点
    
    # 设置搜索参数
    search_parameters = pywrapcp.DefaultRoutingSearchParameters()
    search_parameters.first_solution_strategy = routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC
    
    # 解决问题
    solution = routing.SolveWithParameters(search_parameters)
    
    # 输出解决方案
    if solution:
        total_distance = 0
        total_demand = 0
        for vehicle_id in range(num_vehicles):
            index = routing.Start(vehicle_id)
            plan_output = f"Vehicle {vehicle_id}:\n"
            route_distance = 0
            route_demand = 0
            while not routing.IsEnd(index):
                node_index = routing.IndexToNode(index)
                next_node_index = routing.IndexToNode(solution.Value(routing.NextVar(index)))
                route_distance += routing.GetArcCostForVehicle(node_index, next_node_index, vehicle_id)
                route_demand += demands[node_index]
                plan_output += f" -> {node_index}"
                index = solution.Value(routing.NextVar(index))
            plan_output += f" -> {routing.IndexToNode(index)}\n"
            plan_output += f"Distance of the route: {route_distance}m\n"
            plan_output += f"Demand of the route: {route_demand}\n"
            print(plan_output)
            total_distance += route_distance
            total_demand += route_demand
        print(f"\nTotal distance of all routes: {total_distance}m")
        print(f"Total demand of all routes: {total_demand}")
    else:
        print("No solution found!")

# 示例数据
num_vehicles = 2
num_nodes = 6
vehicle_capacities = [10, 10]
demands = [0, 1, 2, 3, 4, 5]
distances = [[0, 1, 2, 3, 4, 5],
             [1, 0, 1, 2, 3, 4],
             [2, 1, 0, 1, 2, 3],
             [3, 2, 1, 0, 1, 2],
             [4, 3, 2, 1, 0, 1],
             [5, 4, 3, 2, 1, 0]]

# 解决问题
solve_cvrp_without_visiting_all_nodes(num_vehicles, num_nodes, vehicle_capacities, demands, distances)

请注意，这个示例使用Google OR-Tools库来解决CVRP问题。在这个示例中，我们通过设置