From ac48d84a816b518b32ab63ad823421e8e83a578d Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cdo@wip.sh>
Date: Sat, 22 Mar 2025 13:33:38 +0000
Subject: [PATCH] Refactor to extract update() function

---
 main.c | 104 +++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 64 insertions(+), 40 deletions(-)

diff --git a/main.c b/main.c
index b6a63a4..6d103cd 100644
--- a/main.c
+++ b/main.c
@@ -17,6 +17,17 @@
 
 enum { UNKNOWN = 0xfe, KILLER = 0xfd };
 
+typedef enum {
+	FOUND_MINE,
+	FOUND_SAFE,
+	FOUND_NOTHING,
+} update_res_t;
+
+typedef struct {
+	int mines, unknown;
+	puzz_t field;
+} state_t;
+
 static void setadj(puzz_t field, int x, int y, uint8_t from, uint8_t to)
 {
 	for (int yp = y - 1; yp < y + 2; ++yp) {
@@ -46,53 +57,66 @@ static void getadj(puzz_t field, int *x, int *y, uint8_t val)
 	assert(false);
 }
 
+static update_res_t update(state_t *state, int *x_out, int *y_out)
+{
+	state->mines = state->unknown = 0;
+	for (int y = 0; y < HEIGHT; ++y) {
+		for (int x = 0; x < WIDTH; ++x) {
+			state->mines += state->field[x][y] == MINE ? 1 : 0;
+			state->unknown += state->field[x][y] == UNKNOWN ? 1 : 0;
+		}
+	}
+	for (int y = 0; y < HEIGHT; ++y) {
+		for (int x = 0; x < WIDTH; ++x) {
+			if (state->field[x][y] == UNKNOWN || state->field[x][y] == MINE)
+				continue;
+
+			const int mines = countadj(state->field, x, y, MINE);
+			const int unknowns = countadj(state->field, x, y, UNKNOWN);
+			if (unknowns == 0)
+				continue;
+
+			if (mines + unknowns == state->field[x][y]) {
+				setadj(state->field, x, y, UNKNOWN, MINE);
+				return FOUND_MINE;
+			}
+
+			if (mines == state->field[x][y]) {
+				getadj(state->field, &x, &y, UNKNOWN);
+				*x_out = x;
+				*y_out = y;
+				return FOUND_SAFE;
+			}
+		}
+	}
+
+	return FOUND_NOTHING;
+}
+
 static status_t solve(void)
 {
-	puzz_t field;
-	memset(field, UNKNOWN, sizeof(field));
+	state_t state = { .mines = 0, .unknown = WIDTH * HEIGHT };
+	memset(state.field, UNKNOWN, sizeof(puzz_t));
+
+	int x = rand() % WIDTH;
+	int y = rand() % HEIGHT;
 
 	status_t status;
-	int total_mines = 0, total_unknowns = WIDTH * HEIGHT;
 	do {
-		int x = rand() % WIDTH;
-		int y = rand() % HEIGHT;
-
-	probe:
-		if (field[x][y] != MINE && (status = probe(x, y, field)) == DEAD) {
-			field[x][y] = KILLER;
+		if (state.field[x][y] != MINE
+		    && (status = probe(x, y, state.field)) == DEAD)
 			break;
+
+		update_res_t update_res;
+		do
+			update_res = update(&state, &x, &y);
+		while (update_res == FOUND_MINE);
+
+		if (update_res == FOUND_NOTHING) {
+			x = rand() % WIDTH;
+			y = rand() % HEIGHT;
 		}
-
-	update:
-		total_mines = total_unknowns = 0;
-		for (y = 0; y < HEIGHT; ++y) {
-			for (x = 0; x < WIDTH; ++x) {
-				total_mines += field[x][y] == MINE ? 1 : 0;
-				total_unknowns += field[x][y] == UNKNOWN ? 1 : 0;
-			}
-		}
-		for (y = 0; y < HEIGHT; ++y) {
-			for (x = 0; x < WIDTH; ++x) {
-				if (field[x][y] == UNKNOWN || field[x][y] == MINE)
-					continue;
-
-				const int mines = countadj(field, x, y, MINE);
-				const int unknowns = countadj(field, x, y, UNKNOWN);
-				if (unknowns == 0)
-					continue;
-
-				if (mines + unknowns == field[x][y]) {
-					setadj(field, x, y, UNKNOWN, MINE);
-					goto update;
-				}
-
-				if (mines == field[x][y]) {
-					getadj(field, &x, &y, UNKNOWN);
-					goto probe;
-				}
-			}
-		}
-	} while (total_mines < NMINES);
+	} while (state.mines < NMINES);
 
 	return status;
 }