without hashmaps

diff --git a/09b.c b/09b.c
index 3db03bf..23b3a12 100644 (file)
--- a/09b.c
+++ b/09b.c
@@ -1,34 +1,15 @@
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 #include <stdbool.h>
-#include <uthash.h>
+#include <stdint.h>
 
-struct point { int x; int y; };
-struct entry { struct point key; UT_hash_handle hh; };
+struct point { uint8_t x; uint8_t y; };
+bool visited[102][102] = {0};
+int grid[102][102];
 
-bool havevisited(struct entry **visited, int x, int y)
+int basin(int x, int y)
 {
-       struct entry *e = NULL;
-       struct point p;
-       memset(&p, 0, sizeof(p));
-       p.x = x;
-       p.y = y;
-       HASH_FIND(hh, *visited, &p, sizeof(struct point), e);
-       return e;
-}
-
-void addvisited(struct entry **visited, struct point p)
-{
-       struct entry *e = calloc(1, sizeof(struct entry));
-       e->key = p;
-       HASH_ADD(hh, *visited, key, sizeof(struct point), e);
-}
-
-int basin(struct entry **visited, int grid[102][102], int x, int y)
-{
-       struct point stack[1000];
-       memset(stack, 0, sizeof stack);
+       struct point stack[100];
 
        int sp = 0;
        int size = 0;
@@ -38,21 +19,21 @@ int basin(struct entry **visited, int grid[102][102], int x, int y)
        memset(&p, 0, sizeof p);
        while(--sp >= 0) {
                p = stack[sp];
-               if (havevisited(visited, p.x, p.y))
+               if (visited[p.y][p.x])
                        continue;
-               addvisited(visited, p);
+               visited[p.y][p.x] = true;
 
                if (grid[p.y][p.x] == 9)
                        continue;
                size++;
 
-               if (!havevisited(visited, p.x+1, p.y))
+               if (!visited[p.y][p.x+1])
                        stack[sp++] = (struct point){.x=p.x+1, .y=p.y};
-               if (!havevisited(visited, p.x-1, p.y))
+               if (!visited[p.y][p.x-1])
                        stack[sp++] = (struct point){.x=p.x-1, .y=p.y};
-               if (!havevisited(visited, p.x, p.y+1))
+               if (!visited[p.y+1][p.x])
                        stack[sp++] = (struct point){.x=p.x, .y=p.y+1};
-               if (!havevisited(visited, p.x, p.y-1))
+               if (!visited[p.y-1][p.x])
                        stack[sp++] = (struct point){.x=p.x, .y=p.y-1};
        }
        return size;
@@ -60,7 +41,6 @@ int basin(struct entry **visited, int grid[102][102], int x, int y)
 
 int main()
 {
-       int grid[102][102];
        for (int i = 0; i<102; i++)
                for (int j = 0; j<102; j++)
                        grid[i][j] = 9;
@@ -78,11 +58,10 @@ int main()
        }
 
        int tl[3] = {0};
-       struct entry *visited = NULL;
        for (int cy = 1; cy<y; cy++) {
                for (int cx = 1; cx<maxx+1; cx++) {
-                       if (!havevisited(&visited, cx, cy)) {
-                               int s = basin(&visited, grid, cx, cy);
+                       if (!visited[cy][cx]) {
+                               int s = basin(cx, cy);
                                if (s >= tl[0]) {
                                        tl[2] = tl[1];
                                        tl[1] = tl[0];