From 6cabce9380878b79e75e7b9bd2869a671db91087 Mon Sep 17 00:00:00 2001
From: Thomas <thomas@thomasballantine.com>
Date: Mon, 22 Dec 2025 23:58:25 +0000
Subject: [PATCH] m

---
 2015_day_5/Makefile |   7 +++
 2015_day_5/day_5.c  | 138 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 145 insertions(+)
 create mode 100644 2015_day_5/Makefile
 create mode 100644 2015_day_5/day_5.c

diff --git a/2015_day_5/Makefile b/2015_day_5/Makefile
new file mode 100644
index 0000000..e7b14f9
--- /dev/null
+++ b/2015_day_5/Makefile
@@ -0,0 +1,7 @@
+compile:
+	gcc day_5.c -Werror=switch -o day5 -march=native -Ofast -flto
+
+run:
+	./day5
+run2:
+	./day4 2
\ No newline at end of file
diff --git a/2015_day_5/day_5.c b/2015_day_5/day_5.c
new file mode 100644
index 0000000..5f97caa
--- /dev/null
+++ b/2015_day_5/day_5.c
@@ -0,0 +1,138 @@
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+FILE *fptr;
+
+
+struct __attribute__((packed)) {
+    unsigned int w0 : 1;
+    unsigned int w1 : 1;
+    unsigned int w2 : 1;
+    unsigned int w3 : 1;
+    unsigned int w4 : 1;
+    unsigned int f0 : 1;
+} bitfield;
+
+
+//RULES: Must match all 3
+//Contains 3 vowels: aeiou only
+//At least one letter appears twice in a row
+//It does not contain the strings ab, cd, pq, or xy
+int main(){
+
+    fptr = fopen("input", "r");  
+    if(fptr == NULL) {
+        printf("Not able to open the file.");
+    return 1;
+    }
+    long long int line_count = 0;
+    long long int nice_strings_count = 0;
+    long long int new_nice_strings_count = 0;
+    long long int naughty_strings_count = 0;
+    char buffer[266];
+    int cnt_1 = 0;
+    int cnt_2 = 0;
+    int cnt_3 = 0;
+    char compare_1[3];
+    char compare_2[3];
+    while (fgets(buffer, sizeof(buffer), fptr)) {
+        line_count++;
+        bitfield.w0 = 0;
+        bitfield.w1 = 0;
+        bitfield.w2 = 0;
+        bitfield.w3 = 0;
+        bitfield.w4 = 0;
+        bitfield.f0 = 0;
+        cnt_1 = 0;
+        cnt_2 = 0;
+        cnt_3 = 0;
+        //loop 1 aeiou
+        for(int i = 0; i<strlen(buffer); i++){
+            if (buffer[i] == 'a' || buffer[i] == 'e' || buffer[i] == 'i' || buffer[i] == 'o' || buffer[i] == 'u'){
+                cnt_1 = cnt_1 + 1;
+            }
+            if (cnt_1 == 3){
+                bitfield.w0 = 1;
+                printf("break 1\n");
+                break;
+            }
+        }
+        //loop 2: letter repeated
+        for(int i = 1; i<strlen(buffer); i++){
+            if (buffer[i] == buffer[i-1]){
+                cnt_2 = cnt_2 + 1;
+            }
+            if (cnt_2 == 1){
+                bitfield.w1 = 1;
+                printf("break 2\n");
+                break;
+            }
+        }
+        //loop 3: does not contain ab,cd, pq or xy
+
+        for(int i = 0; i< strlen(buffer) - 1; i++){
+            if ((buffer[i] == 'a' && buffer[i+1] == 'b') || (buffer[i] == 'c' && buffer[i+1] == 'd') || (buffer[i] == 'p' && buffer[i+1] == 'q') || (buffer[i] == 'x' && buffer[i+1] == 'y')){
+                bitfield.w2 = 1;
+                printf("break 3\n");
+                break;
+            }
+        }
+        //loop 4: For Part 2: needs to have 2 identical 2 character substrings (separated by at least 1 char)
+        for(int i = 0; i< strlen(buffer) - 1 && bitfield.f0 == 0; i++){
+            sprintf(compare_1,"%.2s", buffer + i);
+                for(int j = 2 + i; j < strlen(buffer) - 1; j++){
+                    sprintf(compare_2,"%.2s", buffer + j);
+                    if(strcmp(compare_1,compare_2) == 0){
+                        bitfield.w3 = 1;
+                        printf("break 4\n");
+                        bitfield.f0 = 1;
+                        break;
+                    }
+                }
+
+
+
+        }
+        bitfield.f0 = 0;
+
+        //It contains at least one letter which repeats with exactly one letter between them, like xyx, abcdefeghi (efe), or even aaa.
+        //loop 5: for part 2: finding matching letters with exactly one letter in between
+        for(int i = 0; i< strlen(buffer) - 2; i++){
+            sprintf(compare_1,"%.1s", buffer + i);
+            sprintf(compare_2,"%.1s", buffer + i + 2);
+            if(strcmp(compare_1,compare_2) ==0){
+                printf("break 5\n");
+                bitfield.w4 = 1;
+                break;
+            }
+
+
+
+        }
+
+        //Thing nice and naughty string counting for Part 1
+        if (bitfield.w1 == 1 && bitfield.w0 == 1 && bitfield.w2 ==0){
+            nice_strings_count = nice_strings_count + 1;
+        }
+        else {
+            naughty_strings_count = naughty_strings_count + 1;
+        }
+
+        //Counting part 2
+        if (bitfield.w3 == 1 && bitfield.w4 == 1){
+            new_nice_strings_count = new_nice_strings_count + 1;
+        }
+
+
+
+        memset(buffer, 0, sizeof(buffer)); // clear the buffer to zero
+
+
+
+
+    }
+    printf("naughty lines: %lli\n",naughty_strings_count);
+    printf("nice lines: %lli\n", nice_strings_count);
+    printf("nice lines part 2: %lli\n",new_nice_strings_count);
+
+}
\ No newline at end of file