commit db96d762add6f00a352663dd6ffd591e9b24e583
Author: wi11-holdsworth <83637728+wi11-holdsworth@users.noreply.github.com>
Date:   Tue Aug 26 20:23:31 2025 +1000

    init

diff --git a/.envrc b/.envrc
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--- /dev/null
+++ b/.envrc
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+use flake
diff --git a/.gitignore b/.gitignore
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+++ b/.gitignore
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+.direnv
diff --git a/README.md b/README.md
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+# Project 1: Maths Puzzles
+
+## Math Puzzle
+- each digit must be 1-9
+- each row contains no repeated digit
+- each column contains no repeated digit
+- all squares on the diagonal line from top left corner to bottom right corner must contain the same value
+- the heading of each row holds either:
+    - the sum of all the digits in that row
+    - the product of all the digits in that row
+- the heading of each column holds either:
+    - the sum of all the digits in that column
+    - the product of all the digits in that column
+
+## Input
+A math puzzle with most/all squares empty **except** for the headings
+
+## Solution
+
+### Structure
+A predicate `puzzle_solution/1` which holds when the argument is a solved math puzzle
+
+### Approach
+Utilise constraint logic programming
+1. unify all squares on the diagonal
+2. check rows are valid
+    1. all distinct
+    2. sum to heading
+    3. product to head
+3. check columns are valid via `transpose/2` 
diff --git a/flake.lock b/flake.lock
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+++ b/flake.lock
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+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1746904237,
+        "narHash": "sha256-3e+AVBczosP5dCLQmMoMEogM57gmZ2qrVSrmq9aResQ=",
+        "rev": "d89fc19e405cb2d55ce7cc114356846a0ee5e956",
+        "revCount": 797896,
+        "type": "tarball",
+        "url": "https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.1.797896%2Brev-d89fc19e405cb2d55ce7cc114356846a0ee5e956/0196c1a7-7ad3-74a9-9d50-1b854aca6d6c/source.tar.gz"
+      },
+      "original": {
+        "type": "tarball",
+        "url": "https://flakehub.com/f/NixOS/nixpkgs/0.1"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
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+++ b/flake.nix
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+{
+  description = "A Nix-flake-based Swi-prolog development environment";
+
+  inputs.nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.1";
+
+  outputs = inputs:
+    let
+      supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      forEachSupportedSystem = f: inputs.nixpkgs.lib.genAttrs supportedSystems (system: f {
+        pkgs = import inputs.nixpkgs { inherit system; };
+      });
+    in
+    {
+      devShells = forEachSupportedSystem ({ pkgs }: {
+        default = pkgs.mkShell {
+          packages = with pkgs; [ swi-prolog ];
+        };
+      });
+    };
+}