Index: aoc2024.c
==================================================================
--- aoc2024.c
+++ aoc2024.c
@@ -4,10 +4,46 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include "aocdailies.h"
 #include "aocutils.h"
+
+/* === aoc202407 =======================================================
+   Part one looks easy
+===================================================================== */
+
+static bool canbetrue(unsigned v, unsigned *a, size_t n) {
+    // for startes let's assume no overflowing
+    if (n == 1) return (v == *a);
+    unsigned tmp = a[1];
+    a[1] = a[0] + tmp;
+    if (canbetrue(v, a+1, n-1)) return true;
+    a[1] = a[0] * tmp;
+    if (canbetrue(v, a+1, n-1)) return true;
+    a[1] = tmp;
+    return false;
+}
+
+void aoc202407(char *data, size_t len) {
+    (void)len; // unused argument
+    unsigned calibrationtotal = 0;
+    char *line = strtok(data, "\n");
+    unsigned number[50], nnumber, maxn = 0;
+    while (line) {
+        char *err;
+        unsigned testvalue = strtoul(line, &err, 10);
+        err += 1; // skip ':'
+        nnumber = 0;
+        while (*err == ' ') {
+            number[nnumber++] = strtoul(err, &err, 10);
+        }
+        if (canbetrue(testvalue, number, nnumber)) calibrationtotal += testvalue;
+        if (nnumber > maxn) { maxn = nnumber; printf("max: %u\n", maxn); }
+        line = strtok(NULL, "\n");
+    }
+    printf("The calibration total is {%u}.\n", calibrationtotal);
+}
 
 /* === aoc202406 =======================================================
    Hmmm, I've done something like this already this year... on day 4
    I need rcmap() moved to aocutils ... done; now it's called `linearize2d`
 Part Two: brute force? It likely is faster than coming up with an algo

Index: aocdailies.c
==================================================================
--- aocdailies.c
+++ aocdailies.c
@@ -4,10 +4,12 @@
 aocfunc *aocselect(unsigned y, unsigned d) {
     aocfunc *p;
     switch (y * 100 + d) {
         default: p = NULL; break;
 
+        //   YYYYdd ==>  aocYYYYdd
+        case 202407: p = aoc202407; break;
         case 202406: p = aoc202406; break;
         case 202405: p = aoc202405; break;
         case 202404: p = aoc202404; break;
         case 202403: p = aoc202403; break;
         case 202402: p = aoc202402; 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 aoc202407;
 aocfunc aoc202406;
 aocfunc aoc202405;
 aocfunc aoc202404;
 aocfunc aoc202403;
 aocfunc aoc202402;