Added solutions for 15, 16, 17, 18 and 19

2 files changed, 69 insertions, 0 deletions

diff --git a/2023/15/15a.c b/2023/15/15a.c
new file mode 100644
index 0000000..16a8fec
--- /dev/null
+++ b/2023/15/15a.c
@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+#define N 100000
+
+char *b, line[N];
+int c, s;
+
+int main() {
+        fgets(line, N, stdin);
+
+        for (b = line, c = 0, s = 0; *b; b++) {
+                if (*b == ',' || *b == '\n') {
+                        s += c;
+                        c = 0;
+                } else
+                        c = (c + (int)*b) * 17 % 256;
+        }
+
+        printf("%d\n", s);
+        return 0;
+}
diff --git a/2023/15/15b.c b/2023/15/15b.c
new file mode 100644
index 0000000..15b97f9
--- /dev/null
+++ b/2023/15/15b.c
@@ -0,0 +1,48 @@
+#include <inttypes.h>
+#include <stdio.h>
+
+#define N 100000
+
+char *b, line[N];
+int64_t c, l, s, n[256], box[256][N];
+
+int main() {
+        fgets(line, N, stdin);
+
+        for (b = line, c = 0; *b != '\n'; b++) {
+                switch (*b) {
+                case ',':
+                        c = 0;
+                        l = 0;
+                        break;
+                case '=':
+                        int64_t i;
+                        for (i = 0; i < n[c]; i++)
+                                if (box[c][i] / 10 == l)
+                                        break;
+                        if (i == n[c]) n[c]++;
+                        box[c][i] = l * 10 + (int)(*(++b)-'0');
+                        break;
+                case '-':
+                        for (int64_t i = 0; i < n[c]; i++) {
+                                if (box[c][i] / 10 == l) {
+                                        for (int j = i+1; j < n[c]; j++)
+                                                box[c][j-1] = box[c][j];
+                                        n[c]--;
+                                }
+                        }
+                        break;
+                default:
+                        c = (c + (int)*b) * 17 % 256;
+                        l = l*256 + (int)*b;
+                        break;
+                }
+        }
+
+        for (int64_t i = 0; i < 256; i++)
+                for (int64_t j = 0; j < n[i]; j++)
+                        s += (i+1) * (j+1) * (box[i][j]%10);
+
+        printf("%" PRId64 "\n", s);
+        return 0;
+}