Index: aoc2015.c
==================================================================
--- aoc2015.c
+++ aoc2015.c
@@ -1,10 +1,40 @@
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include "aocdailies.h"
 #include "aocutils.h"
+
+void aoc201505(char *data, size_t len) {
+    (void)len; // unused argument
+    char *line = strtok(data, "\n"), *vtest;
+    unsigned nice = 0;
+    while (line) {
+        if (!strstr(line, "ab")) {
+            if (!strstr(line, "cd")) {
+                if (!strstr(line, "pq")) {
+                    if (!strstr(line, "xy")) {
+                        for (vtest = line; vtest[1]; vtest++) {
+                            if (vtest[0] == vtest[1]) break;
+                        }
+                        if (vtest[0] == vtest[1]) {
+                            unsigned vowels = 0;
+                            for (vtest = line; *vtest; vtest++) {
+                                if (strchr("aeiou", *vtest)) vowels++;
+                                if (vowels == 3) break;
+                            }
+                            nice += (vowels == 3);
+                        }
+                    }
+                }
+            }
+        }
+        line = strtok(NULL, "\n");
+    }
+    printf("There are %u nice strings.\n", nice);
+}
 
 void aoc201504(char *data, size_t len) {
     data[--len] = 0; // remove newline, adjust `len`
     char longkey[128];
     unsigned extra = 1;

Index: aocdailies.c
==================================================================
--- aocdailies.c
+++ aocdailies.c
@@ -36,12 +36,12 @@
         case 201510: p = aoc201510; break;
         case 201509: p = aoc201509; break;
         case 201508: p = aoc201508; break;
         case 201507: p = aoc201507; break;
         case 201506: p = aoc201506; break;
-        case 201505: p = aoc201505; break;
         #endif
+        case 201505: p = aoc201505; break;
         case 201504: p = aoc201504; break;
         case 201503: p = aoc201503; break;
         case 201502: p = aoc201502; break;
         case 201501: p = aoc201501; break;
 

Index: aocdailies.h
==================================================================
--- aocdailies.h
+++ aocdailies.h
@@ -35,12 +35,12 @@
 aocfunc aoc201510;
 aocfunc aoc201509;
 aocfunc aoc201508;
 aocfunc aoc201507;
 aocfunc aoc201506;
-aocfunc aoc201505;
 #endif
+aocfunc aoc201505;
 aocfunc aoc201504;
 aocfunc aoc201503;
 aocfunc aoc201502;
 aocfunc aoc201501;