From 6fe3c5c1886af8cd6c74b09ef2691b57c4aa41a0 Mon Sep 17 00:00:00 2001
From: damage <damage@devloop.de>
Date: Fri, 24 Jul 2026 20:41:07 +0200
Subject: [PATCH] add step description

---
 sudoku.c | 28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/sudoku.c b/sudoku.c
index 3df1ccc..c213fbb 100644
--- a/sudoku.c
+++ b/sudoku.c
@@ -27,6 +27,7 @@ int sudoku[9][9] = {
 */
 
 // https://www.free-sudoku.com/sudoku.php?dchoix=evil
+/*
 int sudoku[9][9] = {
     {VALUE_UNDEFINED,1,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED},
     {3,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,8,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED},
@@ -38,6 +39,19 @@ int sudoku[9][9] = {
     {1,VALUE_UNDEFINED,VALUE_UNDEFINED,6,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED},
     {5,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,8,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED,VALUE_UNDEFINED}
 };
+*/
+
+int sudoku[9][9] = {
+    {5, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, 1, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED},
+    {VALUE_UNDEFINED, VALUE_UNDEFINED, 4, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, 1, VALUE_UNDEFINED, 2},
+    {7, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, 3, VALUE_UNDEFINED, VALUE_UNDEFINED, 5, VALUE_UNDEFINED},
+    {VALUE_UNDEFINED, VALUE_UNDEFINED, 7, 3, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, 6, VALUE_UNDEFINED},
+    {VALUE_UNDEFINED, 2, VALUE_UNDEFINED, VALUE_UNDEFINED, 6, VALUE_UNDEFINED, VALUE_UNDEFINED, 4, VALUE_UNDEFINED},
+    {VALUE_UNDEFINED, 9, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, 8, 3, VALUE_UNDEFINED, VALUE_UNDEFINED},
+    {VALUE_UNDEFINED, 8, VALUE_UNDEFINED, VALUE_UNDEFINED, 4, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, 2},
+    {4, VALUE_UNDEFINED, 6, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, 7, VALUE_UNDEFINED, VALUE_UNDEFINED},
+    {VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, 1, VALUE_UNDEFINED, VALUE_UNDEFINED, VALUE_UNDEFINED, 9}
+};
 
 void readQ(int num) {
     printf("Enter every number of Q%d from left top to right bottom. Use `0` if on no initial value:\n", num + 1);
@@ -225,9 +239,9 @@ bool isInQuadrat(int q, int val) {
     return false;
 }
 
-void setValue(int q, int f, int val) {
+void setValue(int q, int f, int val, char* rule) {
     sudoku[q][f] = val;
-    printf("=> setting %d in Q %d; F %d\n", val, q, f);
+    printf("=> setting %d in Q %d; F %d (%s)\n", val, q, f, rule);
     //printDumpSudoku();
 }
 
@@ -276,12 +290,14 @@ int main() {
             };
 
             for (int val = 1; val <= 9; val++) {
+	        // val is already set in quadrat, go ahead
                 if (isInQuadrat(q, val)) {
                     continue;
                 }
 
                 int possibleField = FIELD_UNDEFINED;
                 for (int f = 0; f < 9; f++) {
+		    // calculate row and col of current field in quadrant
                     int row = calculateRow(q, f);
                     int col = calculateCol(q, f);
 
@@ -310,12 +326,12 @@ int main() {
 
                 // found possible field? set val
                 if (possibleField > FIELD_UNDEFINED) {
-                    setValue(q, possibleField, val);
+                    setValue(q, possibleField, val, "standard col/row check");
                     somethingChanged = true;
                 }
             }
 
-            // check if only one field is left undefined -> hast to be the one special value
+            // check if only one field is left undefined -> has to be the one special value
             for (int f = 0; f < 9; f++) {
                 // keep in mind that sudoku array might have changed since evaluation
                 // -> ignore already set values
@@ -324,7 +340,7 @@ int main() {
                 }
 
                 if (possbileVal[f] > VALUE_UNDEFINED) {
-                    setValue(q, f, possbileVal[f]);
+                    setValue(q, f, possbileVal[f], "every other value is not possible here");
                     somethingChanged = true;
                 } else {
                     // set to undefined, multiple or any other meta information
@@ -336,4 +352,4 @@ int main() {
     printDumpSudoku();
 
     checkSolution();
-}
\ No newline at end of file
+}