From cf87e5f67ae18767b933edb3b1371696f6b1c582 Mon Sep 17 00:00:00 2001
From: Matthew Sotoudeh <matthewsot@outlook.com>
Date: Fri, 7 Oct 2022 12:46:02 -0700
Subject: algorithms

---
 alg_c.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 alg_c.c

(limited to 'alg_c.c')

diff --git a/alg_c.c b/alg_c.c
new file mode 100644
index 0000000..fd8b7d3
--- /dev/null
+++ b/alg_c.c
@@ -0,0 +1,79 @@
+#include <stdlib.h>
+#include <assert.h>
+#include <stdio.h>
+
+#define MAX(A, B) (((A) > (B)) ? (A) : (B))
+
+int main(int argv, char **argc) {
+    if (argv < 3) {
+        assert(argv > 0);
+        printf("Usage: %s [n] [t]\n", argc[0]);
+        return -1;
+    }
+
+    long n = atoi(argc[1]),
+         t = atoi(argc[2]),
+         s = n - t;
+
+    assert(1 < t && t < n);
+
+    char *a = calloc(n, sizeof(*a)),
+         *w = calloc(n + 1, sizeof(*a));
+
+C1_initialize:
+    for (size_t j = 0; j < s; j++)
+        a[j] = 0;
+    for (size_t j = s; j < n; j++)
+        a[j] = 1;
+    for (size_t j = 0; j <= n; j++)
+        w[j] = 1;
+    size_t r = (s > 0) ? s : t;
+
+C2_visit:
+    for (size_t k = n; k --> 0;)
+        printf("%lu", a[k]);
+    printf("\n");
+
+C3_find_j_and_branch:
+    size_t j = r;
+    while (w[j] == 0) {
+        w[j] = 1;
+        j = j + 1;
+    }
+    if (j == n) return 0;
+    w[j] = 0;
+    if (j % 2 == 1 && a[j] != 0) goto C4_move_right_one;
+    if (j % 2 == 0 && a[j] != 0) goto C5_move_right_two;
+    if (j % 2 == 0 && a[j] == 0) goto C6_move_left_one;
+    if (j % 2 == 1 && a[j] == 0) goto C7_move_left_two;
+
+C4_move_right_one:
+    a[j - 1] = 1;
+    a[j] = 0;
+    if (r == j && j > 1)    r = j - 1;
+    else if (r == j - 1)    r = j;
+    goto C2_visit;
+
+C5_move_right_two:
+    if (a[j - 2] != 0) goto C4_move_right_one;
+    a[j - 2] = 1;
+    a[j] = 0;
+    if (r == j)             r = MAX(j - 2, 1);
+    else if (r == j - 2)    r = j - 1;
+    goto C2_visit;
+
+C6_move_left_one:
+    a[j] = 1;
+    a[j - 1] = 0;
+    if (r == j && j > 1)    r = j - 1;
+    else if (r == j - 1)    r = j;
+    goto C2_visit;
+
+C7_move_left_two:
+    if (a[j - 1] != 0) goto C6_move_left_one;
+    a[j] = 1;
+    a[j - 2] = 0;
+    if (r == j - 2)         r = j;
+    else if (r == j - 1)    r = j - 2;
+    goto C2_visit;
+}
-- 
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