Index: Makefile
==================================================================
--- Makefile
+++ Makefile
@@ -1,6 +1,6 @@
-all: aocdbg aoc aocclang aoctcc
+all: aoc aocdbg aocclang aoctcc
 
 clean:
 	rm aocdbg aoc aocclang aoctcc
 
 aocdbg: *.c *.h

Index: aoc2024.c
==================================================================
--- aoc2024.c
+++ aoc2024.c
@@ -11,11 +11,10 @@
    Oh! another square of text!
    Idea: for all points p with an antenna find all points q>p with
 a corresponding frequency. For each such pair calculate the 2 antinodes
 and add the resulting points (if not there already) to an array.
    The answer to Part One is the number of elements in the array
-TODO: I don't like my `linearize2d` thing! Thinking of a replacement
 ===================================================================== */
 
 void aoc202408(char *data, size_t len) {
     (void)len; // unused argument
     struct TextGrid tg;
@@ -30,16 +29,27 @@
     char *p = data;
     while (*p) {
         while ((*p == '.') || (*p == '\n')) p++;
         if (*p) {
             // p points to an antenna
+            unsigned prow = TGrow(&tg, p), pcol = TGcol(&tg, p);
             char *q = strchr(p+1, *p);
             while (q) {
                 // q points to an antenna of the same type as p
-                printf("p is at (C:%u, R:%u); q is at (C:%u, R:%u)\n",
-                      TGcol(&tg, p), TGrow(&tg, p),
-                      TGcol(&tg, q), TGrow(&tg, q));
+                unsigned qrow = TGrow(&tg, q), qcol = TGcol(&tg, q);
+                int deltarow = (int)qrow - (int)prow;
+                int deltacol = (int)qcol - (int)pcol;
+                printf("p is at (C:%u, R:%u); q is at (C:%u, R:%u) ... delta: (C: %d, R: %d)\n",
+                      pcol, prow, qcol, qrow, deltacol, deltarow);
+                int col1 = (int)pcol - deltacol, row1 = (int)prow - deltarow;
+                if (TGvalid(&tg, row1, col1)) {
+                    printf("antinode at (C:%u, R:%u)\n", col1, row1);
+                }
+                int col2 = (int)qcol + deltacol, row2 = (int)qrow + deltarow;
+                if (TGvalid(&tg, row2, col2)) {
+                    printf("antinode at (C:%u, R:%u)\n", col2, row2);
+                }
                 q = strchr(q+1, *p); // next antenna of this type
             }
             p += 1;
         }
     }