add a couple of days

1 files changed, 89 insertions, 0 deletions

diff --git a/Advent-of-Code-2022/aoc-25/main.c b/Advent-of-Code-2022/aoc-25/main.c
new file mode 100644
index 0000000..c88d918
--- /dev/null
+++ b/Advent-of-Code-2022/aoc-25/main.c
@@ -0,0 +1,89 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if 0
+  #define FILENAME "sample.txt"
+#else
+  #define FILENAME "input.txt"
+#endif
+
+int char_to_int[256] = {
+    ['1'] =  1,
+    ['2'] =  2,
+    ['0'] =  0,
+    ['-'] = -1,
+    ['='] = -2
+};
+
+char int_to_char[5] = {
+    '=', '-', '0', '1', '2'
+};
+
+long long sum = 0;
+
+void encode()
+{
+    signed char num[1000] = {0};
+    size_t num_sz = 0;
+
+    for(long long n = sum; n > 0; n /= 5, num_sz++) {
+        num[num_sz] += n % 5;
+        num[num_sz+1] += num[num_sz]/5;
+        num[num_sz] %= 5;
+
+        if(num[num_sz] == 3) {
+            num[num_sz] = -2;
+            num[num_sz+1] += 1;
+        } else if(num[num_sz] == 4) {
+            num[num_sz] = -1;
+            num[num_sz+1] += 1;
+        }
+    }
+
+    for(int i = num_sz-1; i >= 0; i--) {
+        printf("%c", int_to_char[num[i]+2]);
+    }
+
+    printf("\n");
+}
+
+long long decode(char *num)
+{
+    long long n = 0;
+
+    size_t len = strlen(num);
+    long long power_of_5 = 1;
+
+    for(int i = len-1; i >= 0; i--) {
+        n += power_of_5 * char_to_int[num[i]];
+        power_of_5 *= 5;
+    }
+
+    return n;
+}
+
+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) != NULL) {
+        if(line[strlen(line)-1] == '\n')
+            line[strlen(line)-1] = '\0';
+        sum += decode(line);
+    }
+
+    fclose(fp);
+}
+
+int main(void)
+{
+    parse();
+    encode();
+    return 0;
+}