1 files changed, 47 insertions, 0 deletions
diff --git a/advent-of-code/2022/03/2.c b/advent-of-code/2022/03/2.c
new file mode 100644
index 0000000..f91ea46
--- /dev/null
+++ b/advent-of-code/2022/03/2.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#define BUFSZ 1024
+
+char buf[BUFSZ + 1] = {0};
+
+int table[53] = {0};
+
+int decode(char c) {
+    if (c >= 'A' && c <= 'Z') {
+        return 26 + c - 'A' + 1;
+    }
+    if (c >='a' && c <= 'z') {
+        return c - 'a' + 1;
+    }
+    return -1;
+}
+
+int process(char *buf, int len, int n) {
+    if (n == 1) memset(table, 0, 53 * sizeof(int));
+    for (int i = 0; i < len; i++) {
+        int code = decode(buf[i]);
+        if (table[code] == n - 1) {
+            if (n == 3) return code; 
+            table[code] = n;
+        }
+    }
+    return 0;
+}
+
+
+int main() {
+    FILE *fp = fopen("input", "r");
+    int sum = 0;
+    if (fp == NULL) return -1;
+    int line = 0;
+    while (fgets(buf, BUFSZ, fp)) {
+        if (strlen(buf) <= 1) continue;
+        int len = strlen(buf) - 1;
+        sum += process(buf, len, line % 3 + 1);
+        line++;
+    }
+    printf("%d\n", sum);
+}