new files

Task/Ackermann-function/C/ackermann-function-1.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+
+int ackermann(int m, int n)
+{
+        if (!m) return n + 1;
+        if (!n) return ackermann(m - 1, 1);
+        return ackermann(m - 1, ackermann(m, n - 1));
+}
+
+int main()
+{
+        int m, n;
+        for (m = 0; m <= 4; m++)
+                for (n = 0; n < 6 - m; n++)
+                        printf("A(%d, %d) = %d\n", m, n, ackermann(m, n));
+
+        return 0;
+}

Task/Ackermann-function/C/ackermann-function-2.c

@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int m_bits, n_bits;
+int *cache;
+
+int ackermann(int m, int n)
+{
+        int idx, res;
+        if (!m) return n + 1;
+
+        if (n >= 1<<n_bits) {
+                printf("%d, %d\n", m, n);
+                idx = 0;
+        } else {
+                idx = (m << n_bits) + n;
+                if (cache[idx]) return cache[idx];
+        }
+
+        if (!n) res = ackermann(m - 1, 1);
+        else    res = ackermann(m - 1, ackermann(m, n - 1));
+
+        if (idx) cache[idx] = res;
+        return res;
+}
+int main()
+{
+        int m, n;
+
+        m_bits = 3;
+        n_bits = 20;  /* can save n values up to 2**20 - 1, that's 1 meg */
+        cache = malloc(sizeof(int) * (1 << (m_bits + n_bits)));
+        memset(cache, 0, sizeof(int) * (1 << (m_bits + n_bits)));
+
+        for (m = 0; m <= 4; m++)
+                for (n = 0; n < 6 - m; n++) {
+                        printf("A(%d, %d) = %d\n", m, n, ackermann(m, n));
+
+        return 0;
+}