Zigzag conversion

Signed-off-by: begeekmyfriend <[email protected]>

006_zigzag_conversion/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test zigzag_conversion.c

006_zigzag_conversion/zigzag_conversion.c

@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* convert(char* s, int numRows) {
+    if (numRows <= 1) return s;
+
+    int len = strlen(s);
+    char *new_str = malloc(len + 1);    
+    char *p = new_str;
+    int row = 0;
+    for (row = 0; row < numRows; row++) {
+        int interval1 = numRows + (numRows - 2) - row * 2;
+        int interval2 = 2 * row;
+        int flag = 0;
+        int i = row;
+        while (i < len) {
+            *p++ = s[i];
+            int delta = 0;
+            do {
+                delta = flag == 0 ? interval1 : interval2;
+                flag = !flag;
+            } while (delta == 0);
+            i += delta;
+        }
+    }
+
+    new_str[len] = '\0';
+    return new_str;
+}
+
+int main(int argc, char **argv)
+{
+    if (argc < 3) {
+        fprintf(stderr, "./test string num\n");
+        exit(-1);
+    }
+
+    printf("%s\n", convert(argv[1], atoi(argv[2])));
+    return 0;
+}