From: Mart Lubbers <mart@martlubbers.net>
Date: Thu, 9 Dec 2021 07:00:02 +0000 (+0100)
Subject: day 9 part two inefficient
X-Git-Url: https://git.martlubbers.net/?a=commitdiff_plain;h=609cb2a6836b566e94e69ce0b8d2693b9b2547ad;p=advent21.git

day 9 part two inefficient
---

diff --git a/09b.c b/09b.c
new file mode 100644
index 0000000..a332dd4
--- /dev/null
+++ b/09b.c
@@ -0,0 +1,97 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <limits.h>
+#include <uthash.h>
+
+struct point { int x; int y; };
+struct entry { struct point key; UT_hash_handle hh; };
+
+#define push(x, y) {\
+	if ((x) >= 1 && (y) >= 1 && (x) <= maxx+1 && (y) <= maxy+1)\
+		stack[sp++] = (struct point){x, y};\
+	}
+
+int basin(int grid[102][102], int maxx, int maxy, int x, int y)
+{
+	printf("calculate basin for: %d,%d -- ", x, y);
+	struct point stack[1000];
+	memset(stack, 0, sizeof stack);
+	struct entry *visited = NULL;
+
+	int sp = 0;
+	int size = 0;
+	stack[sp++] = (struct point){.x=x, .y=y};
+
+	struct point p;
+	struct entry *e;
+	memset(&p, 0, sizeof p);
+	while(--sp >= 0) {
+		p = stack[sp];
+		HASH_FIND(hh, visited, &p, sizeof(struct point), e);
+		if (e)
+			continue;
+
+		e = calloc(1, sizeof(struct entry));
+		e->key = p;
+		HASH_ADD(hh, visited, key, sizeof(struct point), e);
+
+		if (grid[p.y][p.x] == 9)
+			continue;
+		size++;
+
+		push(p.x+1, p.y);
+		push(p.x-1, p.y);
+		push(p.x, p.y+1);
+		push(p.x, p.y-1);
+	}
+	printf(" %d\n", size);
+	return size;
+}
+
+void insert(int tl[3], int s)
+{
+	if (s > tl[0] && s <= tl[1])
+		tl[0] = s;
+	if (s > tl[1] && s <= tl[2]) {
+		tl[0] = tl[1];
+		tl[1] = s;
+	}
+	if (s > tl[2]) {
+		tl[0] = tl[1];
+		tl[1] = tl[2];
+		tl[2] = s;
+	}
+}
+
+int main()
+{
+	int grid[102][102];
+	for (int i = 0; i<102; i++)
+		for (int j = 0; j<102; j++)
+			grid[i][j] = 9;
+	int x = 1, y = 1;
+	int maxx = 1;
+	int c = 0;
+	while((c = getchar()) != EOF) {
+		if (c == '\n') {
+			y++;
+			x = 1;
+		} else {
+			maxx = x > maxx ? x : maxx;
+			grid[y][x++] = c-'0';
+		}
+	}
+
+	int tl[3] = {0};
+	for (int cy = 1; cy<y; cy++)
+		for (int cx = 1; cx<maxx+1; cx++)
+			if (grid[cy][cx] < grid[cy+1][cx] &&
+					grid[cy][cx] < grid[cy-1][cx] &&
+					grid[cy][cx] < grid[cy][cx+1] &&
+					grid[cy][cx] < grid[cy][cx-1])
+				insert(tl, basin(grid, maxx, y, cx, cy));
+	printf("%d %d %d\n", tl[0], tl[1], tl[2]);
+	printf("%d\n", tl[0]*tl[1]*tl[2]);
+}
diff --git a/Makefile b/Makefile
index 68c8c53..c1bccfe 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 CFLAGS:=-Wall -Wextra -O3
 LFLAGS:=-f
 
-BINARIES:=$(foreach num,$(shell seq -f '%02.0f' 1 8),$(num)a $(num)b)
+BINARIES:=$(foreach num,$(shell seq -f '%02.0f' 1 9),$(num)a $(num)b)
 
 all: $(BINARIES)