Arbitrages: First working version

Arbitrages/cs412_arbitrages_a.py

@@ -0,0 +1,83 @@
+"""
+name: Nicholas Tamassia
+
+Honor Code and Acknowledgments:
+
+        This work complies with the JMU Honor Code.
+
+       Comments here on your code and submission.
+"""
+
+import math
+from collections import defaultdict
+
+
+def find_arbitrage(graph: dict[str, dict[str, float]]) -> list[str] | None:
+    weights: dict[str, float] = {c: math.inf for c in graph}
+    prev: dict[str, str | None] = {c: None for c in graph}
+    start: str = list(graph.keys())[0]
+
+    weights[start] = 0
+    for _ in range(len(graph) - 1):
+        for src in graph:
+            for dest, rate in graph[src].items():
+                weight: float = -math.log(rate)
+                if weights[src] + weight < weights[dest]:
+                    weights[dest] = weights[src] + weight
+                    prev[dest] = src
+
+    node: str | None = None
+    for src in graph:
+        for dest, rate in graph[src].items():
+            weight: float = -math.log(rate)
+            if weights[src] + weight < weights[dest]:
+                node = dest
+                prev[dest] = src
+                break
+        if node is not None:
+            break
+
+    if node is None:
+        return
+
+    for _ in range(len(graph)):
+        node = prev[node]
+
+    path = [node]
+    while True:
+        node = prev[node]
+        path.append(node)
+        if node == path[0]:
+            break
+
+    path.reverse()
+
+    return path
+
+
+def main():
+    n: int = int(input().strip())
+    graph: dict[str, dict[str, float]] = defaultdict(dict)
+
+    for _ in range(n):
+        vals: list[str] = input().strip().split()
+        src: str = vals[0]
+        dest: str = vals[1]
+        rate: float = float(vals[2])
+        graph[src][dest] = rate
+
+    path = find_arbitrage(graph)
+    if path is not None:
+        print("Arbitrage Detected")
+        print(" => ".join(path))
+
+        factor = 1.0
+        for i in range(len(path) - 1):
+            factor *= graph[path[i]][path[i + 1]]
+        print(f"{factor:.5f} factor increase")
+    else:
+        print("No Arbitrage Detected")
+
+
+if __name__ == "__main__":
+    main()

Arbitrages/inputs/sample1.txt

@@ -0,0 +1,5 @@
+4
+USD EUR 0.82
+EUR JPY 129.7
+JPY TRY 12
+TRY USD 0.0008

Arbitrages/inputs/sample2.txt

@@ -0,0 +1,3 @@
+2
+USD GBP 1.0
+GBP USD 1.0

devenv.lock

@@ -3,10 +3,10 @@
     "devenv": {
       "locked": {
         "dir": "src/modules",
-        "lastModified": 1757570236,
+        "lastModified": 1762789285,
         "owner": "cachix",
         "repo": "devenv",
-        "rev": "c57bded76fa6a885ab1dee2c75216cc23d58b311",
+        "rev": "379dd49a2ae3470e216cf07bfee4326e3c5a5baf",
         "type": "github"
       },
       "original": {
@@ -19,10 +19,10 @@
     "flake-compat": {
       "flake": false,
       "locked": {
-        "lastModified": 1747046372,
+        "lastModified": 1761588595,
         "owner": "edolstra",
         "repo": "flake-compat",
-        "rev": "9100a0f413b0c601e0533d1d94ffd501ce2e7885",
+        "rev": "f387cd2afec9419c8ee37694406ca490c3f34ee5",
         "type": "github"
       },
       "original": {
@@ -40,10 +40,10 @@
         ]
       },
       "locked": {
-        "lastModified": 1757588530,
+        "lastModified": 1762441963,
         "owner": "cachix",
         "repo": "git-hooks.nix",
-        "rev": "b084b2c2b6bc23e83bbfe583b03664eb0b18c411",
+        "rev": "8e7576e79b88c16d7ee3bbd112c8d90070832885",
         "type": "github"
       },
       "original": {
@@ -74,10 +74,10 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1755783167,
+        "lastModified": 1761313199,
         "owner": "cachix",
         "repo": "devenv-nixpkgs",
-        "rev": "4a880fb247d24fbca57269af672e8f78935b0328",
+        "rev": "d1c30452ebecfc55185ae6d1c983c09da0c274ff",
         "type": "github"
       },
       "original": {