working

day3/c/aoc_day3.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define ARR_LEN (1000)
+
+
+// read file, dump into diagnostics and count bits, do part one stuff
+// return answer for part one
+int d3_part_one(int* diagnostics, size_t diag_len,
+			int* bit_ct, size_t bit_ct_len);
+
+// returns answer for part two
+int d3_part_two(const int* const diagnostics, size_t diag_len,
+				const int* const bit_ct, size_t bit_len,
+				int power_consumption);
+
+int main(int argc, char** argv)
+{
+	int diagnostic_arr[ARR_LEN];
+	int bit_ct[12];
+
+	memset(diagnostic_arr, 0, ARR_LEN * sizeof(int));
+	memset(bit_ct, 0, 12 * sizeof(int));
+
+
+	int power_consumption = d3_part_one(diagnostic_arr, ARR_LEN, bit_ct, 12);
+	printf("(Part 1 Answer) Power Consumption: %d\n", power_consumption);
+
+
+	return 0;
+}
+
+
+// returns status of init
+int d3_part_one(int* diagnostics, size_t diag_len,
+			int* bit_ct, size_t bit_ct_len)
+{
+	FILE* fp = fopen("input.txt", "r");
+	if(!fp)
+	{
+		printf("Failed to open file for reading...\n");
+		exit(-1);
+	}
+	char* line = NULL;
+	size_t len = 0;
+	for(int ind = 0; ind < ARR_LEN; ind++)
+	{
+		ssize_t rc = getline(&line, &len, fp);
+		if(rc == -1)
+		{
+			printf("EXITING ABNORMALLY\n");
+			exit(-1);
+		}
+		diagnostics[ind] = strtol(line, NULL, 2);
+		for(int bit = 0; bit < bit_ct_len; bit++)
+		{
+			bit_ct[bit] += ((diagnostics[ind] & (1 << bit))>>bit);
+		}
+	}
+
+	fclose(fp);
+
+	int gamma = 0;
+	int epsilon = 0;
+	for(int bit = 0; bit < bit_ct_len; bit++)
+	{
+		gamma += ((bit_ct[bit] > (ARR_LEN >> 1))<<bit);
+	}
+	epsilon = (~gamma) & 0xFFF;
+	return gamma * epsilon;
+}
+
+// returns answer for part two
+// we can use the answer from part 1 to cut out a lot of unnecessary instructions
+int d3_part_two(const int* const diagnostics, size_t diag_len,
+				const int* const bit_ct, size_t bit_len,
+				int power_consumption)
+{
+	int ans = 0;
+
+	return ans;
+}