Committing days 1-4

04/04.c

@@ -0,0 +1,100 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#define DEFAULT_FILE        "input.txt"
+#define STRBUF_LEN          200
+#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)) {
+            if (points) points = points * 2;
+            else points = 1;
+        }
+    }
+
+    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};
+    uint32_t totalpoints = 0;
+
+    while (fgets(strbuf, STRBUF_LEN, file))
+    {
+        if (strbuf[0] == '\n') break;
+        parse_line(strbuf, winning_nums, holding_nums);
+        totalpoints += calculate_points(winning_nums, holding_nums);
+    }
+
+    printf("Total Points: %d\n", totalpoints);
+
+    return 0;
+}