Merge pull request #1955 from waltman/branch-for-challenge-069

Branch for challenge 069

4 files changed, 115 insertions, 0 deletions

diff --git a/challenge-069/walt-mankowski/c/.gitignore b/challenge-069/walt-mankowski/c/.gitignore
new file mode 100644
index 0000000000..ac77297bfe
--- /dev/null
+++ b/challenge-069/walt-mankowski/c/.gitignore
@@ -0,0 +1,2 @@
+ch-1
+ch-2
diff --git a/challenge-069/walt-mankowski/c/Makefile b/challenge-069/walt-mankowski/c/Makefile
new file mode 100644
index 0000000000..8694263018
--- /dev/null
+++ b/challenge-069/walt-mankowski/c/Makefile
@@ -0,0 +1,23 @@
+C = /usr/bin/cc
+INCLDIRS =
+LIBDIRS =
+LIBS =
+CFLAGS = -std=c18 -Wall -O3 $(INCLDIRS)
+OBJECTS1 = ch-1.o
+OBJECTS2 = ch-2.o
+
+all: ch-1 ch-2
+
+%.o: %.c
+	$(C) $(CFLAGS) -c $<
+
+ch-1: $(OBJECTS1)
+	$(C) -o $@ $(OBJECTS1) $(LIBDIRS) $(LIBS)
+
+ch-2: $(OBJECTS2)
+	$(C) -o $@ $(OBJECTS2) $(LIBDIRS) $(LIBS)
+
+clean:
+	rm -f *~
+	rm -f *.o
+	rm -f ch-1 ch-2
diff --git a/challenge-069/walt-mankowski/c/ch-1.c b/challenge-069/walt-mankowski/c/ch-1.c
new file mode 100644
index 0000000000..a5e15845c6
--- /dev/null
+++ b/challenge-069/walt-mankowski/c/ch-1.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+const size_t min(const size_t a, const size_t b) {
+    return a <= b ? a : b;
+}
+
+int is_strobogrammatic(const long long n) {
+    char s[20];
+    sprintf(s, "%lld", n);
+    const size_t len = strlen(s);
+    for (size_t i = 0; i < min(len/2+1, len); i++) {
+        const size_t j = len-1-i;
+        switch (s[i]) {
+        case '0':
+            if (s[j] != '0')
+                return 0;
+            break;
+        case '1':
+            if (s[j] != '1')
+                return 0;
+            break;
+        case '6':
+            if (s[j] != '9')
+                return 0;
+            break;
+        case '8':
+            if (s[j] != '8')
+                return 0;
+            break;
+        case '9':
+            if (s[j] != '6')
+                return 0;
+            break;
+        default:
+            return 0;
+        }
+    }
+    return 1;
+}
+
+int main(int argc, char *argv[]) {
+    const long long A = atoll(argv[1]);
+    const long long B = atoll(argv[2]);
+
+    for (long long i = A; i <= B; i++)
+        if (is_strobogrammatic(i))
+            printf("%lld\n", i);
+
+    return 0;
+}
diff --git a/challenge-069/walt-mankowski/c/ch-2.c b/challenge-069/walt-mankowski/c/ch-2.c
new file mode 100644
index 0000000000..21347722ce
--- /dev/null
+++ b/challenge-069/walt-mankowski/c/ch-2.c
@@ -0,0 +1,38 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+const size_t min(const size_t a, const size_t b) {
+    return a <= b ? a : b;
+}
+
+void switch_rev(char *s) {
+    const size_t len = strlen(s);
+    for (size_t i = 0; i < min(len/2+1, len); i++) {
+        const size_t j = len-1-i;
+        const char tmp = s[i];
+        s[i] = s[j] == '0' ? '1' : '0';
+        s[j] = tmp  == '0' ? '1' : '0';
+    }
+}
+
+const char *S(const int n) {
+    const size_t len = (1 << n) - 1;
+    char *s = malloc(len);
+    s[0] = '\0';
+
+    for (int i = 1; i <= n; i++) {
+        const size_t eos = (1 << (i-1)) - 1;
+        strcpy(s+eos+1, s);
+        s[eos] = '0';
+        switch_rev(s+eos+1);
+    }
+    return s;
+}
+
+int main(int argc, char *argv[]) {
+    const int n = atoi(argv[1]);
+    puts(S(n));
+    
+    return 0;
+}