From 62ae713bd2391e8196848fc037999a356856ae9d Mon Sep 17 00:00:00 2001
From: Bill Rossi <bassguitarbill@gmail.com>
Date: Wed, 25 Dec 2024 06:15:52 -0500
Subject: [PATCH] C 2024 day 18 part 2

---
 c/2024/18/ram_run.c | 119 ++++++++++++++++++++++++--------------------
 1 file changed, 64 insertions(+), 55 deletions(-)

diff --git a/c/2024/18/ram_run.c b/c/2024/18/ram_run.c
index abcd7ab..462ccd7 100644
--- a/c/2024/18/ram_run.c
+++ b/c/2024/18/ram_run.c
@@ -19,6 +19,51 @@ typedef struct Grid {
   Node grid[DIMENSION][DIMENSION];
 } Grid;
 
+void grid_dijkstra(Grid *g) {
+  Node* queue[QUEUE_LENGTH];
+  queue[0] = &(g->grid[0][0]);
+  int queue_start = 0;
+  int queue_end = 1;
+
+  g->grid[0][0].c = '*';
+  g->grid[0][0].cost = 0;
+
+  while (queue_start != queue_end) {
+    // get first element of queue
+    Node* n = queue[queue_start++];
+    queue_start %= QUEUE_LENGTH;
+    n->c = ' ';
+    // add its neighbors to the queue
+    if (n->x - 1 >= 0 && g->grid[n->x - 1][n->y].c == '.') {
+      g->grid[n->x - 1][n->y].c = '*';
+      g->grid[n->x - 1][n->y].cost = n->cost + 1;
+      queue[queue_end++] = &(g->grid[n->x - 1][n->y]);
+      queue_end %= 200;
+    }
+
+    if (n->y - 1 >= 0 && g->grid[n->x][n->y - 1].c == '.') {
+      g->grid[n->x][n->y - 1].c = '*';
+      g->grid[n->x][n->y - 1].cost = n->cost + 1;
+      queue[queue_end++] = &(g->grid[n->x][n->y - 1]);
+      queue_end %= 200;
+    }
+
+    if (n->x + 1 < DIMENSION && g->grid[n->x + 1][n->y].c == '.') {
+      g->grid[n->x + 1][n->y].c = '*';
+      g->grid[n->x + 1][n->y].cost = n->cost + 1;
+      queue[queue_end++] = &(g->grid[n->x + 1][n->y]);
+      queue_end %= 200;
+    }
+
+    if (n->y + 1 < DIMENSION && g->grid[n->x][n->y + 1].c == '.') {
+      g->grid[n->x][n->y + 1].c = '*';
+      g->grid[n->x][n->y + 1].cost = n->cost + 1;
+      queue[queue_end++] = &(g->grid[n->x][n->y + 1]);
+      queue_end %= 200;
+    }
+  }
+}
+
 int main() {
   char *line;
   Grid g;
@@ -33,66 +78,30 @@ int main() {
   }
 
   int x, y;
-  int i = 0;
+
+  //while ((line = aoc_read_line()) != NULL) {
+  for (int i = 0; i < 1024; i++) {
+    line = aoc_read_line();
+    sscanf(line, "%d,%d", &x, &y);
+    g.grid[x][y].c = '#';
+  }
+
+  Grid original_grid;
+  memcpy(&original_grid, &g, sizeof(Grid));
+
+  grid_dijkstra(&g);
+
+  printf("Part 1: %d\n", g.grid[DIMENSION - 1][DIMENSION - 1].cost);
 
   while ((line = aoc_read_line()) != NULL) {
     sscanf(line, "%d,%d", &x, &y);
-    if (i++ < 1024) g.grid[x][y].c = '#';
+    original_grid.grid[x][y].c = '#';
+    memcpy(&g, &original_grid, sizeof(Grid));
+    grid_dijkstra(&g);
+    if (g.grid[DIMENSION - 1][DIMENSION - 1].cost == -1) break;
   }
 
-  Node* queue[QUEUE_LENGTH];
-  queue[0] = &(g.grid[0][0]);
-  int queue_start = 0;
-  int queue_end = 1;
-
-  g.grid[0][0].c = '*';
-  g.grid[0][0].cost = 0;
-
-  while (queue_start != queue_end) {
-    // get first element of queue
-    Node* n = queue[queue_start++];
-    queue_start %= QUEUE_LENGTH;
-    n->c = ' ';
-    // add its neighbors to the queue
-    if (n->x - 1 >= 0 && g.grid[n->x - 1][n->y].c == '.') {
-      g.grid[n->x - 1][n->y].c = '*';
-      g.grid[n->x - 1][n->y].cost = n->cost + 1;
-      queue[queue_end++] = &(g.grid[n->x - 1][n->y]);
-      queue_end %= 200;
-    }
-
-    if (n->y - 1 >= 0 && g.grid[n->x][n->y - 1].c == '.') {
-      g.grid[n->x][n->y - 1].c = '*';
-      g.grid[n->x][n->y - 1].cost = n->cost + 1;
-      queue[queue_end++] = &(g.grid[n->x][n->y - 1]);
-      queue_end %= 200;
-    }
-
-    if (n->x + 1 < DIMENSION && g.grid[n->x + 1][n->y].c == '.') {
-      g.grid[n->x + 1][n->y].c = '*';
-      g.grid[n->x + 1][n->y].cost = n->cost + 1;
-      queue[queue_end++] = &(g.grid[n->x + 1][n->y]);
-      queue_end %= 200;
-    }
-
-    if (n->y + 1 < DIMENSION && g.grid[n->x][n->y + 1].c == '.') {
-      g.grid[n->x][n->y + 1].c = '*';
-      g.grid[n->x][n->y + 1].cost = n->cost + 1;
-      queue[queue_end++] = &(g.grid[n->x][n->y + 1]);
-      queue_end %= 200;
-    }
-  }
-
-  /*
-  for (int i = 0; i < DIMENSION; i++) {
-    for (int j = 0; j < DIMENSION; j++) {
-      printf("%c", g.grid[j][i].c);
-    }
-    printf("\n");
-  }
-  */
-
-  printf("Part 1: %d", g.grid[DIMENSION - 1][DIMENSION - 1].cost);
+  printf("Part 2: %d,%d\n", x, y);
 
   aoc_free();
   exit(0);