# Travelling Salesman - Logistics Problem

**URL:** <https://discourse.nodered.org/t/travelling-salesman-logistics-problem/100045>\
**Category:** Share Your Projects\
**Created:** [30 December 2025 08:53 UTC](https://discourse.nodered.org/t/travelling-salesman-logistics-problem/100045 "2025-12-30T08:53:28Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![dynamicdave](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dynamicdave/32/96_2.png) [@dynamicdave](https://discourse.nodered.org/u/dynamicdave)\
**Post date:** [30 December 2025 08:53 UTC](https://discourse.nodered.org/t/travelling-salesman-logistics-problem/100045/1 "2025-12-30T08:53:28Z")

</div>

One of my IoT students has been exploring the classical Travelling Salesman Problem and came across an excellent [write-up](https://www.mathematics.pitt.edu/sites/default/files/TSP.pdf) produced by a graduate at the University of Pittsburgh.

The document contains a substantial amount of mathematical theory; however, **from page 15 onwards** it presents a **fully worked example** showing how the problem can be solved **manually**. This example uses the _Nearest Neighbour_ heuristic, which is relatively straightforward to model programmatically. I therefore encouraged the student to implement this approach in Python as a practical exercise (as shown below).

```auto
dist = [
    [0, 8, 8, 6, 7],
    [8, 0, 12, 10, 11],
    [8, 12, 0, 5, 9],
    [6, 10, 5, 0, 15],
    [7, 11, 9, 15, 0]
]

N = len(dist)
current = 0
visited = [False] * N
visited[current] = True

path = [current]
total_distance = 0

for _ in range(N - 1):
    next_city = None
    min_dist = 1e9

    for city in range(N):
        if not visited[city] and dist[current][city] < min_dist:
            min_dist = dist[current][city]
            next_city = city

    visited[next_city] = True
    path.append(next_city)
    total_distance += min_dist
    current = next_city

total_distance += dist[current][path[0]]
path.append(path[0])

print("Greedy distance:", total_distance)
print("Path:", path)

```

As a personal challenge, I took his Python script, converted it to JavaScript using an online Python-to-JavaScript tool, and then placed the converted code into a Node-RED function node. This resulted in the simple flow shown below.  
 ![tues_travelling_salesman_flow](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/5/0/5025135a2c09802ad2fb0ec470fc6601d23eda23.png)

```auto
[{"id":"24eb715b6b856fce","type":"tab","label":"Travelling_Salesman_Problem","disabled":false,"info":"","env":[]},{"id":"140e2b6541a0e6fc","type":"function","z":"24eb715b6b856fce","name":"Travelling Salesman calcs","func":"const dist = [\n [0, 8, 8, 6, 7],\n [8, 0, 12, 10, 11],\n [8, 12, 0, 5, 9],\n [6, 10, 5, 0, 15],\n [7, 11, 9, 15, 0]\n];\n\nconst N = dist.length;\nlet current = 0;\nconst visited = Array(N).fill(false);\nvisited[current] = true;\n\nconst path = [current];\nlet total_distance = 0;\n\nfor (let i = 0; i < N - 1; i++) {\n let next_city = null;\n let min_dist = 1e9;\n\n for (let city = 0; city < N; city++) {\n if (!visited[city] && dist[current][city] < min_dist) {\n min_dist = dist[current][city];\n next_city = city;\n }\n }\n\n visited[next_city] = true;\n path.push(next_city);\n total_distance += min_dist;\n current = next_city;\n}\n\n// Return to start\ntotal_distance += dist[current][path[0]];\npath.push(path[0]);\n\nmsg.payload =\n \"Greedy distance: \" + total_distance +\n \"\\nPath: \" + JSON.stringify(path);\n\nreturn msg;\n","outputs":1,"timeout":0,"noerr":0,"initialize":"","finalize":"","libs":[],"x":310,"y":240,"wires":[["4d0947a041ac8a6f"]]},{"id":"5aa55d037231cd41","type":"inject","z":"24eb715b6b856fce","name":"Trigger","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"1","payloadType":"num","x":110,"y":240,"wires":[["140e2b6541a0e6fc"]]},{"id":"4d0947a041ac8a6f","type":"debug","z":"24eb715b6b856fce","name":"Show results","active":true,"tosidebar":true,"console":true,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":540,"y":240,"wires":[]}]

```

Hope you have fun trying it out with Node-RED and/or Python.

---

<div class="post-metadata">

**Author:** ![gregorius](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/gregorius/32/73816_2.png) [@gregorius](https://discourse.nodered.org/u/gregorius)\
**Post date:** [30 December 2025 11:22 UTC](https://discourse.nodered.org/t/travelling-salesman-logistics-problem/100045/2 "2025-12-30T11:22:50Z")

</div>

Have you tried simulating this in [NetLogo](https://netlogo.org)? It would really be a nice visualisation in NetLogo.

As a bonus: NetLogo can actually run [JS](https://github.com/NetLogo/NodeJS-Extension) and [Python](https://github.com/NetLogo/Python-Extension) via extensions.

I mention this because to visual the travelling salesman _solution_ is probably really nice ... along with visualising the source code 😉