App2_Greedy2.py

# this greedy approach

import math
import timeit
start = timeit.default_timer()

def euclidean_distance(x1, y1, x2, y2):
    return math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)

def orienteering_problem_greedy(input_file, output_file):
    # Read input from the file
    with open(input_file, 'r') as file:
        lines = file.readlines()

    # Parse the input
    Tmax, P = map(int, lines[0].split())
    points = []
    for line in lines[1:]:
        x, y, score = map(float, line.split())
        points.append((x, y, score))

    # Calculate the distance matrix
    n = len(points)
    distance_matrix = [[0] * n for _ in range(n)]
    for i in range(n):
        for j in range(i+1, n):  # Utilize symmetry of the distance matrix
            dist = euclidean_distance(
                points[i][0], points[i][1], points[j][0], points[j][1])
            distance_matrix[i][j] = dist
            distance_matrix[j][i] = dist

    # Sort the points by score in descending order
    sorted_points = sorted(points, key=lambda x: x[2], reverse=True)

    # Greedy algorithm
    path = [0]  # Starting from the first point (starting point)
    current_time = 0
    current_score = 0
    visited = [False] * n
    visited[0] = True

    while current_time < Tmax:
        remaining_time = Tmax - current_time
        max_score = float('-inf')
        max_index = None

        for i in range(1, n):
            if not visited[i] and remaining_time >= distance_matrix[path[-1]][i]:
                if sorted_points[i][2] > max_score:
                    max_score = sorted_points[i][2]
                    max_index = i

        if max_index is None:
            break

        path.append(max_index)
        current_time += distance_matrix[path[-2]][max_index]
        current_score += max_score
        visited[max_index] = True

    # Write the output to the file
    with open(output_file, 'w') as file:
        file.write(f"Path: {', '.join(map(str, path))}\n")
        file.write(f"Total Profit: {current_score}")

    print(f"Path: {path}")
    print(f"Total Profit: {current_score}")

# Usage example
input_file = 'Dataset/set_66_1_050.txt'
output_file = 'Results/set_66_1_050_App2.txt'
orienteering_problem_greedy(input_file, output_file)

stop = timeit.default_timer()
print('Time: ', stop - start)