rename repo, subdir for yearly challenges

2020/day05/ex2-c.c

@@ -0,0 +1,53 @@
+/* ex2-c: Advent2020 game, day 5/game 2
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+static int seats[128][8];
+
+int str2int(str)
+    char *str;
+{
+    int res=0;
+    while (*str) {
+        res <<= 1;
+        if (*str == 'B' || *str == 'R')
+            res ^= 1;
+        str++;
+    }
+    return res;
+}
+
+void print_seats()
+{
+    int i, j;
+    printf("seats:\n");
+    for (i=0; i<128; i++) {
+        printf("%03d : ", i);
+        for (j=0; j<8; ++j)
+            printf("%d ", seats[i][j]);
+        printf("\n");
+    }
+}
+
+int main(ac, av)
+    char **av;
+{
+    int cur, count=0;
+    char rowstr[80], colstr[80], line[80];
+    int *pseats=(int *)seats;
+
+    while (fgets(line, sizeof line, stdin)) {
+        count++;
+        sscanf(line, "%[FB]%[RL]", rowstr, colstr);
+        cur=(str2int(rowstr)<<3) ^ str2int(colstr);
+        *(pseats+cur)=1;
+    }
+    for (; *pseats == 0; ++pseats)
+        ;
+    for (; *pseats == 1; ++pseats)
+        ;
+    printf("%s : lines=%d seat=%ld\n", *av, count, pseats-(int *)seats);
+    exit (0);
+}