Committing days 1-4

04/04-part2.c

@@ -0,0 +1,117 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#define DEFAULT_FILE        "input.txt"
+#define STRBUF_LEN          200
+#define NUM_CARDS           202
+#define WINNING_NUM_SIZE    10
+#define HOLDING_NUM_SIZE    25
+#define ISDIGIT(X)      (X >= '0' && X <= '9')
+
+void parse_nums(char *str, uint8_t *nums, uint8_t len)
+{
+    uint8_t i = 0;
+    uint8_t digit_idx = 0;
+    char c;
+    uint8_t num = 0;
+
+    for (i = 0; i < len; i++)
+    {
+        num = 0;
+        digit_idx = (i * 3);
+        c = str[digit_idx];
+        if (ISDIGIT(c)) num = (c - '0') * 10;
+        num += str[digit_idx + 1] - '0';
+        nums[i] = num;
+    }
+}
+
+void parse_line(char *str, uint8_t *winning_nums, uint8_t *holding_nums)
+{
+    while (*str != ':') str++;
+    str += 2;
+    parse_nums(str, winning_nums, WINNING_NUM_SIZE);
+
+    while (*str != '|') str++;
+    str += 2;
+    parse_nums(str, holding_nums, HOLDING_NUM_SIZE);
+}
+
+bool num_in_set(uint8_t num, uint8_t *set, uint8_t len)
+{
+    uint8_t i = 0;
+    for (i = 0; i < len; i++)
+    {
+        if (num == set[i]) return true;
+    }
+
+    return false;
+}
+
+uint32_t calculate_points(uint8_t *winning_nums, uint8_t *holding_nums)
+{
+    uint32_t points = 0;
+    uint8_t i = 0;
+    for (i = 0; i < HOLDING_NUM_SIZE; i++)
+    {
+        if (num_in_set(holding_nums[i], winning_nums, WINNING_NUM_SIZE)) points++;
+    }
+
+    return points;
+}
+
+int main(int argc, char **argv)
+{
+    // Get filename as an argument, defaults to "input.txt"
+    char *path = (argc > 1) ? argv[1] : DEFAULT_FILE;
+
+    if (!path)
+    {
+        printf("Requires input file.\n");
+        return 1;
+    }
+
+    FILE *file = fopen(path, "r");
+
+    if (!file)
+    {
+        printf("Could not find file.");
+        return 1;
+    }
+
+    char strbuf[STRBUF_LEN] = {0};
+    uint8_t winning_nums[WINNING_NUM_SIZE] = {0};
+    uint8_t holding_nums[HOLDING_NUM_SIZE] = {0};
+    uint64_t points = 0;
+    uint64_t card_copies[NUM_CARDS] = { [0 ... NUM_CARDS-1] = 1 };
+    uint8_t i = 0;
+    uint8_t copyidx = 0;
+    uint8_t cardidx = 0;
+
+    for (cardidx = 0; cardidx < NUM_CARDS; cardidx++)
+    {
+        fgets(strbuf, STRBUF_LEN, file);
+        if (strbuf[0] == '\n') break;
+        parse_line(strbuf, winning_nums, holding_nums);
+        points = calculate_points(winning_nums, holding_nums);
+        for (i = 0; i < points; i++)
+        {
+            // Add copy of card for every point
+            if (cardidx + i < NUM_CARDS)
+                card_copies[cardidx + i + 1] = card_copies[cardidx + i + 1] + card_copies[cardidx];
+            else
+                break;
+        }
+    }
+
+    points = 0;
+    for (i = 0; i < NUM_CARDS; i++)
+    {
+        points += card_copies[i];
+    }
+
+    printf("Total cards: %d", points);
+
+    return 0;
+}