Index: aoc2024.c
==================================================================
--- aoc2024.c
+++ aoc2024.c
@@ -4,10 +4,39 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include "aocdailies.h"
 #include "aocutils.h"
+
+/* === aoc202422 =======================================================
+===================================================================== */
+static long long unsigned mix(long long unsigned a, long long unsigned b) {
+    long long unsigned tmp = a ^ b;
+    return tmp;
+}
+
+static long long unsigned prune(long long unsigned a) {
+    return a % 16777216;
+}
+
+void aoc202422(char *data, size_t len) {
+    (void)len; // unused argument
+    long long unsigned sum2000 = 0;
+    char *key = strtok(data, "\n");
+    while (key) {
+        long long unsigned secret;
+        if (sscanf(key, "%llu", &secret) != 1) break;
+        for (int k = 0; k < 2000; k++) {
+            secret = prune(mix(secret * 64, secret));
+            secret = prune(mix(secret / 32, secret));
+            secret = prune(mix(secret * 2048, secret));
+        }
+        sum2000 += secret;
+        key = strtok(NULL, "\n");
+    }
+    printf("The sum of all 2000th secrets is {%llu}.\n", sum2000);
+}
 
 /* === aoc202409 =======================================================
    WOW! input consists of a 20,000 long string of numbers!
    Make an array of blocks, each with either -1 or the fileid
    For Part Two: make an array of blocks with the encoded value of

Index: aocdailies.c
==================================================================
--- aocdailies.c
+++ aocdailies.c
@@ -5,10 +5,11 @@
     aocfunc *p;
     switch (y * 100 + d) {
         default: p = NULL; break;
 
         //   YYYYdd ==>  aocYYYYdd
+        case 202422: p = aoc202422; break;
         case 202409: p = aoc202409; break;
         case 202408: p = aoc202408; break;
         case 202407: p = aoc202407; break;
         case 202406: p = aoc202406; break;
         case 202405: p = aoc202405; break;

Index: aocdailies.h
==================================================================
--- aocdailies.h
+++ aocdailies.h
@@ -4,10 +4,11 @@
 #include <stddef.h>
 
 typedef void aocfunc(char *, size_t);
 aocfunc *aocselect(unsigned, unsigned);
 
+aocfunc aoc202422;
 aocfunc aoc202409;
 aocfunc aoc202408;
 aocfunc aoc202407;
 aocfunc aoc202406;
 aocfunc aoc202405;