1 files changed, 71 insertions, 0 deletions

diff --git a/2023/05/5b.c b/2023/05/5b.c
new file mode 100644
index 0000000..aeac8c0
--- /dev/null
+++ b/2023/05/5b.c
@@ -0,0 +1,71 @@
+/* For part 2 we save ranges as (first, last) instead of (first, length) */
+
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define N 10000
+
+#define MIN(a, b) ((a)<(b)?(a):(b))
+#define MAX(a, b) ((a)>(b)?(a):(b))
+
+bool isnum(char c) { return c >= '0' && c <= '9'; }
+
+void append(int64_t dst[][2], int64_t src[][2], int64_t *nr, int64_t *nnr) {
+        for (int i = 0; i < *nnr; i++) {
+                dst[i+*nr][0] = src[i][0];
+                dst[i+*nr][1] = src[i][1];
+        }
+        *nr += *nnr;
+        *nnr = 0;
+}
+
+int64_t readl(int64_t nums[], char *buf) {
+        int64_t i;
+        for (i = 0; *buf; buf++) {
+                if (!isnum(*buf)) continue;
+                nums[i++] = atoll(buf);
+                while (isnum(*buf)) buf++;
+        }
+        return i;
+}
+
+int main() {
+        char *buf, line[N];
+        int64_t i, li, ri, m, nr, nnr, r[3], range[N][2], next[N][2], aux[N];
+
+        nnr = readl(aux, fgets(line, N, stdin)) / 2;
+        for (i = 0; i < nnr; i++) {
+                next[i][0] = aux[2*i];
+                next[i][1] = aux[2*i+1] + next[i][0] - 1;
+        }
+
+        for (nr = 0; (buf = fgets(line, N, stdin)) != NULL; ) {
+                if (!isnum(*buf)) {
+                        append(range, next, &nr, &nnr);
+                        continue;
+                }
+
+                readl(r, buf);
+                for (i = 0; i < nr; i++) {
+                        li = range[i][0];
+                        ri = range[i][1];
+                        if (li > ri || r[1] > ri || r[1]+r[2]-1 < li) continue;
+                        range[i][1] = MIN(ri, r[1]-1);
+                        next[nnr][0] = MAX(li, r[1]) + r[0]-r[1];
+                        next[nnr++][1] = MIN(ri, r[1]+r[2]-1) + r[0]-r[1];
+                        range[nr][0] = MAX(li, r[1]+r[2]);
+                        range[nr++][1] = ri;
+                }
+        }
+
+        append(range, next, &nr, &nnr);
+        for (i = 0, m = -1; i < nr; i++)
+                if (range[i][0] <= range[i][1])
+                        m = m == -1 || m > range[i][0] ? range[i][0] : m;
+
+        printf("%" PRId64 "\n", m);
+        return 0;
+}