Best attempt at part 2. Did not finish.

08/08-part2.c

@@ -0,0 +1,179 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+
+#define DEFAULT_FILE        "input.txt"
+#define STRBUF_LEN          300
+#define ISDIGIT(X)          (X >= '0' && X <= '9')
+#define NUM_AS              200
+
+#define HASHMAP_SIZE    17576 // 26 * 26 * 26
+
+typedef struct _node
+{
+    char letters[3];
+    int left;
+    int right;
+} node;
+
+int hashnode(char *str)
+{
+    bool err = false;
+
+    if (str[0] < 'A' || str[0] > 'Z') err = true;
+    if (str[1] < 'A' || str[1] > 'Z') err = true;
+    if (str[2] < 'A' || str[2] > 'Z') err = true;
+
+    if (err)
+    {
+        printf("Error in hashnode!");
+        return -1;
+    }
+
+    int first = str[0] - 'A';
+    int second = str[1] - 'A';
+    int third = str[2] - 'A';
+    return (first * 26 * 26) + (second * 26) + third;
+}
+
+bool all_zs(node *nodes, int *as, int numas)
+{
+    int i = 0;
+    for (i = 0; i < numas; i++)
+    {
+        int current_hash = as[i];
+        node current_node = nodes[current_hash];
+        if (current_node.letters[2] != 'Z') return false;
+    }
+    return true;
+}
+
+int count_jumps_to_zzz(char *lrbuf, int start, node *nodes)
+{
+    int instructionidx = 0;
+    int currenthash = start;
+    int numjumps = 0;
+
+    while(currenthash != HASHMAP_SIZE - 1)
+    {
+        if (lrbuf[instructionidx] != 'L' && lrbuf[instructionidx] != 'R') instructionidx = 0;
+        bool is_left = lrbuf[instructionidx] == 'L';
+        instructionidx++;
+
+        currenthash = is_left ? nodes[currenthash].left : nodes[currenthash].right;
+        numjumps++;
+    }
+    return numjumps;
+}
+
+int count_jumps_endsin_z(char *lrbuf, int start, node *nodes)
+{
+    int instructionidx = 0;
+    int currenthash = start;
+    int numjumps = 0;
+
+    while(nodes[currenthash].letters[2] != 'Z')
+    {
+        if (lrbuf[instructionidx] != 'L' && lrbuf[instructionidx] != 'R') instructionidx = 0;
+        bool is_left = lrbuf[instructionidx] == 'L';
+        instructionidx++;
+
+        currenthash = is_left ? nodes[currenthash].left : nodes[currenthash].right;
+        numjumps++;
+    }
+    return numjumps;
+}
+
+int count_jumps_to_cycle(char *lrbuf, int start, node *nodes)
+{
+    int instructionidx = 0;
+    int currenthash = start;
+    int numjumps = 0;
+
+    do
+    {
+        if (lrbuf[instructionidx] != 'L' && lrbuf[instructionidx] != 'R') instructionidx = 0;
+        bool is_left = lrbuf[instructionidx] == 'L';
+        instructionidx++;
+
+        currenthash = is_left ? nodes[currenthash].left : nodes[currenthash].right;
+        numjumps++;
+    }
+    while(currenthash != start);
+
+    return numjumps;
+}
+
+int main(int argc, char **argv)
+{
+    // Get filename as an argument, if there is one
+    char *path = (argc > 1) ? argv[1] : DEFAULT_FILE;
+
+    if (!path)
+    {
+        printf("Requires input file.\n");
+        return 1;
+    }
+
+    FILE *file = fopen(path, "r");
+    char strbuf[STRBUF_LEN] = {0};
+    char lrbuf[STRBUF_LEN] = {0};
+
+    if (!file)
+    {
+        printf("Could not find file.");
+        return 1;
+    }
+
+    // Begin Challenge
+
+    node nodes[HASHMAP_SIZE];
+    int start_hashes[NUM_AS];
+
+    fgets(lrbuf, STRBUF_LEN, file);
+    fgets(strbuf, STRBUF_LEN, file);
+    
+    while(fgets(strbuf, STRBUF_LEN, file))
+    {
+        node current;
+        int hash = hashnode(strbuf);
+        int left = hashnode(strbuf + 7);
+        int right = hashnode(strbuf + 12);
+
+        memcpy(nodes[hash].letters, strbuf, sizeof(char) * 3);
+        nodes[hash].left = left;
+        nodes[hash].right = right;
+    }
+
+    int i = 0;
+    int numas = 0;
+    for (i = 0; i < HASHMAP_SIZE; i += 26)
+    {
+        if (nodes[i].letters[2] != 'A') continue;
+        start_hashes[numas] = i;
+        numas++;
+        printf("Start: %c%c%c\n", nodes[i].letters[0], nodes[i].letters[1], nodes[i].letters[2]);
+    }
+
+
+    int instructionidx = 0;
+    uint64_t numjumps = 0;
+    while (!all_zs(nodes, start_hashes, numas))
+    {
+        if (lrbuf[instructionidx] != 'L' && lrbuf[instructionidx] != 'R') instructionidx = 0;
+        bool is_left = lrbuf[instructionidx] == 'L';
+        instructionidx++;
+
+        for (i = 0; i < numas; i++)
+        {
+            int current_hash = start_hashes[i];
+            start_hashes[i] = is_left ? nodes[current_hash].left : nodes[current_hash].right;
+        }
+        numjumps++;
+    }
+
+    printf("Numjumps: %lu\n", numjumps);
+
+    return 0;
+}

08/input4.txt

@@ -0,0 +1,10 @@
+LR
+
+CCA = (AAB, XXX)
+AAB = (XXX, AAZ)
+AAZ = (AAB, XXX)
+BBA = (BBB, XXX)
+BBB = (BBC, BBC)
+BBC = (BBZ, BBZ)
+BBZ = (BBB, BBB)
+XXX = (XXX, XXX)