From beaa3cfd61868b9e5b5b9b411445d1481362f3da Mon Sep 17 00:00:00 2001
From: Jonas Zeunert <jonas@zeunert.org>
Date: Mon, 19 Feb 2024 18:55:27 +0100
Subject: [PATCH] Impl: Get possible values from row

---
 src/playfield.rs     |  4 ++--
 src/sudoku_solver.rs | 26 +++++++++++++++++++++++---
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/src/playfield.rs b/src/playfield.rs
index 952786c..99f7d54 100644
--- a/src/playfield.rs
+++ b/src/playfield.rs
@@ -2,7 +2,7 @@ use std::fmt;
 
 #[derive(PartialEq, Debug, Clone)]
 pub struct Playfield {
-    size: usize,
+    pub size: usize,
     pub fields: Vec<Vec<Field>>,
     pub open_fields: Vec<usize>,
 }
@@ -20,7 +20,7 @@ impl Playfield {
 
         playfield.parse(field);
 
-        return playfield;
+        playfield
     }
 
     fn parse(&mut self, field: &String) {
diff --git a/src/sudoku_solver.rs b/src/sudoku_solver.rs
index a2ba2ed..c7ea286 100644
--- a/src/sudoku_solver.rs
+++ b/src/sudoku_solver.rs
@@ -1,3 +1,5 @@
+use std::collections::HashSet;
+
 use crate::playfield::Field;
 use crate::playfield::Playfield;
 
@@ -5,7 +7,7 @@ pub struct SudokuSolver {
     playfield: Playfield,
 }
 
-impl<'a> SudokuSolver {
+impl SudokuSolver {
     pub fn new(playfield: &Playfield) -> SudokuSolver {
         Self {
             playfield: playfield.clone(),
@@ -18,17 +20,33 @@ impl<'a> SudokuSolver {
     fn populate_possible_values(&self) {
         for open_field in &self.playfield.open_fields {}
     }
-    fn possible_values_from_row(&self, row: Vec<Field>) -> Vec<u32> {}
+    fn possible_values_from_row(&self, row: &Vec<Field>) -> Vec<u32> {
+        let max_value = self.playfield.size as u32;
+        let possible_values: HashSet<u32> = (1..max_value + 1).collect();
+
+        let populated_values: HashSet<u32> = row
+            .iter()
+            .filter(|field| field.value.is_some())
+            .map(|v| v.value.unwrap())
+            .collect();
+
+        possible_values
+            .symmetric_difference(&populated_values)
+            .map(|v| *v)
+            .collect()
+    }
 }
 #[cfg(test)]
 mod tests {
     use crate::sudoku_solver::SudokuSolver;
     use crate::Playfield;
+
     fn create_test_playfield(input: &str, size: usize) -> Playfield {
         Playfield::new(&input.to_string(), size)
     }
     mod solve {
         use super::*;
+
         #[test]
         fn simple() {
             let playfield = create_test_playfield("1 2 3 2 3 1 3 1 0", 3);
@@ -42,13 +60,15 @@ mod tests {
     mod populate_possible_values {
         mod possible_values_from_row {
             use super::super::*;
+
             #[test]
             fn simple() {
                 let playfield = create_test_playfield("1 2 0 1 2 0 1 2 0", 3);
                 let expected = vec![3];
 
                 let possible_values =
-                    SudokuSolver::new(&playfield).possible_values_from_row(playfield.fields[0]);
+                    SudokuSolver::new(&playfield).possible_values_from_row(&playfield.fields[0]);
+
                 assert_eq!(possible_values, expected);
             }
         }