# A Novel Application Based on a Heuristic Approach for Planning Itineraries of One-Day Tourist
## 1 Introduction
### Contribution of the Paper  
From the analysis of the above reported studies, the OP is not suitable in case the PoIs need to be selected and exchanged among different itineraries, like outward and return paths of a one day trip, because of time constraint. In this case, it is necessary to implement a multi-level algorithm to be able to consult the tourist on any relocation of PoIs in the tour. To these aims, we applied the Travel Salesman Problem (TSP) [39; 40; 41] method that involves finding the shortest route through n nodes that begins and ends at the same city and visitsevery node. The TSP is among the best-known combinatorial optimization problems and has been intensely studied by researchers in various research fields.  
In this paper, we aim to determine the optimal itinerary for the one-day tourist, maximizing the number of PoIs to be visited in the outward and return path, and at the same time minimizing the travel times taking into account the tourist preferences and hard time constraints. The idea is to allow the tourist to select the preferred PoIs to be visited on the first part of the day, i.e., in the outward trip, and on the second part of the day, i.e., in the return trip, respectively. We formulate our optimization problem on the basis of Graph theory, TSP and multi-level algorithms. We model the city PoIs network on the basis of the graph theory, where the nodes represent the various attractions (PoI) of the city and two separate graphs are derived. The tourist can select the PoIs of the starting graph to be visited with high priority in the outward and return journeys, respectively. In our application the tourist is part of the multi-algorithms approach interacting with it and taking decisions for one-day tourist. The proposed approach plans the tourist itinerary, minizing travel times based on the TSP algorithm, taking into account the priority list of PoIs and the decisions of the user. The TSP is used in this paper since it allows to consider a first itinerary solution including all the PoIs of the city that is refined by the multi-level algorithms interacting with the tourists. In detail, compared with the analyzed works, this paper presents the following novelties:  
* an innovative multi-level algorithm approach is proposed to determine the optimal roundtrip path: the outward and return journeys are specified and customized, minimizing the total travel time, including the visiting time of each PoI.
* the number of attractions to be visited is maximized and is splitted between the outward and return path in order to improve the visiting experience on the basis of user preferences.
* the tourist is seen as an active and informed user who directly interacts with the system for the optimal planning of both the outward and return journeys, not only providing initial inputs and preferences but taking decisions at intermediate stages of the approach.  
The rest of the paper is organized as follows: Section 2 describes the one-day tourist itinerary planning problem; Section 3 presents the Multi-level algorithm approach for the itinerary planning while Section 4 provides the analysis of the algorithms performance and complexity; Section 5 demonstrates the effectiveness of the proposed approach by a case study focusing on the cruise tourist in the city of Bari and Section 6 provides the conclusions and future works perspectives.