Set up python environment for easier development

.envrc

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+use flake

.gitignore

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+.direnv/
+__pycache__/
+.pytest_cache/
+.ruff_cache/
+result

1-Two-Sum/Solution.py

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-class Solution:
-    def twoSum(self, nums: List[int], target: int) -> List[int]:
-        

flake.lock

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+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1784497964,
+        "narHash": "sha256-vlHUuqAcbcH2RKmHbPiuQzbv1pnzzavXnI62RD0bqCU=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "241313f4e8e508cb9b13278c2b0fa25b9ca27163",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  outputs = { self, nixpkgs }:
+    let
+      system = "x86_64-linux";
+      pkgs = nixpkgs.legacyPackages.${system};
+    in {
+      devShells.${system}.default = pkgs.mkShell {
+        packages = with pkgs; [
+          python313
+          ruff              # lint + format
+          basedpyright      # LSP / type checking
+          python313Packages.pytest
+          entr
+        ];
+      };
+    };
+}

new.sh

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+#!/usr/bin/env bash
+d="problems/$1"; mkdir -p "$d"
+cat > "$d/solution.py" <<'EOF'
+class Solution:
+    def solve(self):
+        pass
+EOF
+cat > "$d/solution_test.py" <<'EOF'
+from solution import Solution
+def test_solve():
+    assert Solution().solve() is None
+EOF

pyproject.toml

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+[tool.ruff]
+line-length = 100
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "UP", "B", "SIM"]
+
+[tool.pytest.ini_options]
+testpaths = ["."]
+python_files = ["*_test.py"]