day 4

1 files changed, 76 insertions, 0 deletions

diff --git a/Advent-of-Code-2022/aoc-4/main.c b/Advent-of-Code-2022/aoc-4/main.c
new file mode 100644
index 0000000..56dfcfd
--- /dev/null
+++ b/Advent-of-Code-2022/aoc-4/main.c
@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#if 0
+  #define PART part1
+#else
+  #define PART part2
+#endif
+
+#if 0
+  #define FILENAME "sample.txt"
+#else
+  #define FILENAME "input.txt"
+#endif
+
+int res = 0;
+
+void part1(int *longer, int *shorter)
+{
+    if(longer[0] <= shorter[0] &&
+       longer[1] >= shorter[1])
+        res++;
+}
+
+void part2(int *longer, int *shorter)
+{
+    if((shorter[0] >= longer[0] && shorter[0] <= longer[1]) ||
+       (shorter[1] >= longer[0] && shorter[1] <= longer[1]))
+        res++;
+}
+
+void parse()
+{
+    FILE *fp = fopen(FILENAME, "r");
+    if(!fp) {
+        fprintf(stderr, "ERROR: Could not open file: %s\n", FILENAME);
+        exit(1);
+    }
+
+    char line[256];
+    while(fgets(line, sizeof(line), fp))
+    {
+        int range1[2];
+        int range2[2];
+
+        char *r1 = strtok(line, ",");
+        char *r2 = strtok(NULL, ",");
+        assert(strtok(NULL, ",") == NULL);
+
+        range1[0] = atoi(strtok(r1, "-"));
+        range1[1] = atoi(strtok(NULL, "-"));
+        assert(strtok(NULL, "-") == NULL);
+
+        range2[0] = atoi(strtok(r2, "-"));
+        range2[1] = atoi(strtok(NULL, "-"));
+        assert(strtok(NULL, "-") == NULL);
+
+        int len1 = range1[1] - range1[0] + 1;
+        int len2 = range2[1] - range2[0] + 1;
+        int *longer  = (len1 > len2) ? range1 : range2;
+        int *shorter = (len1 > len2) ? range2 : range1;
+
+        PART(longer, shorter);
+    }
+
+    fclose(fp);
+}
+
+int main(void)
+{
+    parse();
+    printf("%d\n", res);
+    return 0;
+}