From 536cb5922f4c8cd1db7e1707ba797201c8267e1f Mon Sep 17 00:00:00 2001
From: David Phillips <david@sighup.nz>
Date: Sun, 10 Mar 2019 21:58:20 +1300
Subject: Implement board solving check

---
 solve.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 97 insertions(+), 5 deletions(-)

diff --git a/solve.c b/solve.c
index 0a1cb69..d9bc01d 100644
--- a/solve.c
+++ b/solve.c
@@ -219,25 +219,117 @@ int board_is_filled(struct cell (*b)[9][9])
 	return 0;
 }
 
+/*
+ * Check if all of the rows on are correctly solved on a board
+ * Returns 0 for all rows correctly solved
+ */
 int board_rows_are_solved(struct cell (*b)[9][9])
 {
-	return -1;
+	int row_has[9] = {0};
+	int val = 0;
+	int x = 0;
+	int y = 0;
+
+	for (y = 0; y < 9; y++) {
+		memset(row_has, 0, sizeof(row_has));
+		for (x = 0; x < 9; x++) {
+			val = (*b)[x][y].val;
+			if (val == 0) {
+				return -1;
+			}
+			if (row_has[val - 1]) {
+				DEBUG_LOG("Invalid board: Row %d duplicate %d\n", y, val);
+				return -1;
+			}
+			row_has[val - 1] = 1;
+		}
+	}
+
+	return 0;
 }
 
+/*
+ * Check if all of the columns on are correctly solved on a board
+ * Returns 0 for all columns correctly solved
+ */
 int board_cols_are_solved(struct cell (*b)[9][9])
 {
-	return -1;
+	int col_has[9] = {0};
+	int val = 0;
+	int x = 0;
+	int y = 0;
+
+	for (x = 0; x < 9; x++) {
+		memset(col_has, 0, sizeof(col_has));
+		for (y = 0; y < 9; y++) {
+			val = (*b)[x][y].val;
+			if (val == 0) {
+				return -1;
+			}
+			if (col_has[val - 1]) {
+				DEBUG_LOG("Invalid board: Column %d duplicate %d\n", x, val);
+				return -1;
+			}
+			col_has[val - 1] = 1;
+		}
+	}
+
+	return 0;
 }
 
+/*
+ * Check if one of the nine 3x3 blocks is correctly solved on a board
+ * Returns 0 for a correctly solved 3x3
+ */
+int board_3_is_solved(struct cell (*b)[9][9], int cx, int cy)
+{
+	int col_has[9] = {0};
+	int val = 0;
+	int x = 0;
+	int y = 0;
+
+	cx *= 3;
+	cy *= 3;
+
+	for (x = cx; x < cx + 3; x++) {
+		for (y = cy; y < cy + 3; y++) {
+			val = (*b)[x][y].val;
+			if (val == 0) {
+				return -1;
+			}
+			if (col_has[val - 1]) {
+				DEBUG_LOG("Invalid board: 3x3 %d duplicate %d\n", x, val);
+				return -1;
+			}
+			col_has[val - 1] = 1;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Check if all of the nine 3x3 blocks are correctly solved on a board
+ * Returns 0 for correctly solved 3x3s
+ */
 int board_3s_are_solved(struct cell (*b)[9][9])
 {
-	return -1;
+	int ret = 0;
+	int x = 0;
+	int y = 0;
+	for (x = 0; x < 3; x++) {
+		for (y = 0; y < 3; y++) {
+			ret = board_3_is_solved(b, x, y);
+			if (ret)
+				return ret;
+		}
+	}
+	return ret;
 }
 
 /*
  * Check if a board is solved.
- * Returns -1 isf the board is unsolved
- * Returns 0 if the board is solved
+ * Returns 0 if the board is solved correctly
  */
 int board_is_solved(struct cell (*b)[9][9])
 {
-- 
cgit v1.1