From fc40ca960b4d96378b2b15802ff34f2ead5a4df3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20V=C3=B6geli?= <stefan.voegeli@srf.ch>
Date: Mon, 6 Nov 2023 13:13:57 +0100
Subject: [PATCH] Add code for shortest path

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 1 file changed, 229 insertions(+)
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+# 06.11.2023
+
+- [06.11.2023](#06112023)
+  - [Resources](#resources)
+  - [Try and retry](#try-and-retry)
+    - [Packing a backpack](#packing-a-backpack)
+    - [Traveling salesmen](#traveling-salesmen)
+    - [Shortest path problem](#shortest-path-problem)
+
+## Resources
+
+- [Wikipedia - Travelling salesman problem](https://en.wikipedia.org/wiki/Travelling_salesman_problem)
+- [Wikipedia - Shortest path problem](https://en.wikipedia.org/wiki/Shortest_path_problem)
+
+## Try and retry
+
+### Packing a backpack
+
+### Traveling salesmen
+
+### Shortest path problem
+
+Trying to come up with a solution to find the shortest path to visit a list of friends. Each friend can only be visited once.
+
+```javascript
+const hans = "hans"
+const leia = "leia"
+const jana = "jana"
+const petra = "petra"
+const louis = "louis"
+const ina = "ina"
+
+const stops = [
+  {
+    name: hans,
+    destinations: [
+      {
+        name: ina,
+        distance: 2
+      },
+      {
+        name: leia,
+        distance: 3
+      },
+      {
+        name: jana,
+        distance: 3
+      },
+      {
+        name: petra,
+        distance: 3
+      },
+      {
+        name: louis,
+        distance: 5
+      }
+    ]
+  },
+  {
+    name: petra,
+    destinations: [
+      {
+        name: hans,
+        distance: 3
+      },
+      {
+        name: jana,
+        distance: 4
+      },
+      {
+        name: ina,
+        distance: 5
+      },
+      {
+        name: leia,
+        distance: 6
+      },
+      {
+        name: louis,
+        distance: 7
+      }
+    ]
+  },
+  {
+    name: ina,
+    destinations: [
+      {
+        name: hans,
+        distance: 2
+      },
+      {
+        name: jana,
+        distance: 2
+      },
+      {
+        name: louis,
+        distance: 3
+      },
+      {
+        name: petra,
+        distance: 5
+      },
+      {
+        name: leia,
+        distance: 8
+      }
+    ]
+  },
+  {
+    name: jana,
+    destinations: [
+      {
+        name: leia,
+        distance: 1
+      },
+      {
+        name: louis,
+        distance: 2
+      },
+      {
+        name: ina,
+        distance: 3
+      },
+      {
+        name: hans,
+        distance: 3
+      },
+      {
+        name: petra,
+        distance: 4
+      }
+    ]
+  },
+  {
+    name: leia,
+    destinations: [
+      {
+        name: jana,
+        distance: 1
+      },
+      {
+        name: louis,
+        distance: 2
+      },
+      {
+        name: hans,
+        distance: 3
+      },
+      {
+        name: petra,
+        distance: 6
+      },
+      {
+        name: ina,
+        distance: 8
+      }
+    ]
+  },
+  {
+    name: louis,
+    destinations: [
+      {
+        name: jana,
+        distance: 2
+      },
+      {
+        name: leia,
+        distance: 2
+      },
+      {
+        name: ina,
+        distance: 3
+      },
+      {
+        name: hans,
+        distance: 5
+      },
+      {
+        name: petra,
+        distance: 7
+      }
+    ]
+  }
+]
+const solutions = [];
+const maxTries = stops.length * stops.length;
+for (let i = 0; i < stops.length; i++) {
+  let currentTries = 0;
+  while (currentTries < maxTries) {
+    let currentSolution = {
+      stops: [stops[i].name],
+      distance: 0
+    };
+    let hasShortestDistance = solutions.length > 0;
+    let shortestDistance = hasShortestDistance ? solutions.sort((a, b) => {
+      if (a.distance == b.distance) return 0;
+      if (a.distance > b.distance) return 1;
+      return -1;
+    })[0] : null;
+    let stopAdded = false;
+    let isTooLong = false;
+    while (true) {
+      stopAdded = false;
+      for (let destination of stops[i].destinations) {
+        if (currentSolution.stops.indexOf(destination.name) > -1) {
+          continue;
+        }
+        currentSolution.stops.push(destination.name);
+        currentSolution.distance += destination.distance;
+        if (hasShortestDistance && shortestDistance && currentSolution.distance >= shortestDistance.distance) {
+          isTooLong = true;
+        }
+        stopAdded = true;
+        break;
+      }
+      if (!stopAdded || isTooLong) {
+        break;
+      }
+    }
+
+    if (!isTooLong && currentSolution.stops.length == stops.length) {
+      solutions.push(currentSolution);
+    }
+    isTooLong = false;
+    currentTries++;
+  }
+}
+```
+