From 27bef1109d733733b9ebb989ef905e2f072f1619 Mon Sep 17 00:00:00 2001
From: Zander Thannhauser <zthannhauser@gmail.com>
Date: Sun, 15 Jun 2025 19:45:05 -0500
Subject: [PATCH] instead of sparse-lists, why not boolean arrays?

---
 main.c                             | 28 +--------
 spikes/boolean-array-or-2.c        |  0
 spikes/boolean-array.c             | 97 ++++++++++++++++++++++++++++++
 spikes/sorted-sparse-list-remove.c |  5 ++
 4 files changed, 104 insertions(+), 26 deletions(-)
 create mode 100644 spikes/boolean-array-or-2.c
 create mode 100644 spikes/boolean-array.c
 create mode 100644 spikes/sorted-sparse-list-remove.c

diff --git a/main.c b/main.c
index bfcfa16..e6f76e0 100644
--- a/main.c
+++ b/main.c
@@ -531,24 +531,12 @@ void calculate_simplifications(void)
         if (done.headtails[head] < index)
         {
             if (prevhead == -1)
-            {
-                assert(done.headtails[head] == head);
-                
                 done.next[head] = index;
-            }
             else
-            {
-                int tophalftail = done.headtails[prevhead - 1];
-                
-                assert(tophalftail != -1);
-                
-                done.next[tophalftail] = index;
-            }
+                done.next[tophalftail] = done.headtails[prevhead - 1];
         }
         else
-        {
             done.head = index;
-        }
         
         int n = ~index & M;
         int tail = index & 1 ? index : index | (n & -n), prevtail = -1;
@@ -563,21 +551,9 @@ void calculate_simplifications(void)
         if (index < done.headtails[tail])
         {
             if (prevtail == -1)
-            {
-                assert(done.headtails[tail] == tail);
-                
-                assert(done.in[tail]);
-                
                 done.next[index] = tail;
-            }
             else
-            {
-                int bottomhalfhead = done.headtails[prevtail + 1];
-                
-                assert(bottomhalfhead != -1);
-                
-                done.next[index] = bottomhalfhead;
-            }
+                done.next[index] = done.headtails[prevtail + 1];
         }
         else
         {
diff --git a/spikes/boolean-array-or-2.c b/spikes/boolean-array-or-2.c
new file mode 100644
index 0000000..e69de29
diff --git a/spikes/boolean-array.c b/spikes/boolean-array.c
new file mode 100644
index 0000000..04457c6
--- /dev/null
+++ b/spikes/boolean-array.c
@@ -0,0 +1,97 @@
+
+#include <stdbool.h>
+#include <assert.h>
+#include <stdio.h>
+
+#define N (256)
+
+#define M (255)
+
+struct boolist {
+    int data[8][256];
+} list = {};
+
+void insert(int e)
+{
+    printf("insert(e = %i);\n", e);
+    
+    assert(!list.data[0][e]);
+    
+    for (int k = 0; k < 8 && !list.data[k][e >> k]++; k++);
+}
+
+void delete(int e)
+{
+    printf("delete(e = %i);\n", e);
+    
+    assert(list.data[0][e]);
+    
+    for (int k = 0; k < 8 && !--list.data[k][e >> k]; k++);
+}
+
+void print()
+{
+    puts("print():");
+    
+    void walk(int k, int i)
+    {
+        if (k >= 0)
+        {
+            int* a = &list.data[k][i >> k];
+            
+            if (a[0]) walk(k - 1, i);
+            
+            if (a[1]) walk(k - 1, i + (1 << k));
+        }
+        else
+        {
+            printf("  " "%i\n", i);
+        }
+    }
+    
+    walk(7, 0);
+}
+
+int main()
+{
+    print();
+    
+    insert(42);
+    
+    print();
+    
+    insert(101);
+    
+    print();
+    
+    delete(42);
+    
+    print();
+    
+    insert(34);
+    
+    print();
+    
+    insert(35);
+    
+    print();
+    
+    insert(36);
+    
+    print();
+    
+    delete(35);
+    
+    print();
+    
+    return 0;
+}
+
+
+
+
+
+
+
+
+
diff --git a/spikes/sorted-sparse-list-remove.c b/spikes/sorted-sparse-list-remove.c
new file mode 100644
index 0000000..626dc5c
--- /dev/null
+++ b/spikes/sorted-sparse-list-remove.c
@@ -0,0 +1,5 @@
+
+// we need to implement this one
+
+// should be fairly easy
+