add problem 6 add test function

Author: supercoderhawk

C/1-50/6-ZigZag-Conversion.c

@@ -1,4 +1,64 @@
 /*
+ * The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this:
+ * (you may want to display this pattern in a fixed font for better legibility)
+ *
+ * P   A   H   N
+ * A P L S I I G
+ * Y   I   R
+ *
+ * convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR".
+ *
  * Created by supercoderhawk on 2017/7/24.
  */
+#include 
+#include 
+#include 
 
+char *convert(char *s, int numRows) {
+    if (numRows == 1)
+        return s;
+
+    char *p = s;
+    int length = 0, index = 0;
+    while (*p != '\0') {
+        length++;
+        p++;
+    }
+
+    char *zigzag = (char *) malloc(sizeof(char) * (length + 1));
+    char **table = (char **) malloc(sizeof(char *) * numRows);
+    int tableIndex[numRows];
+    for (int i = 0; i < numRows; i++) {
+        table[i] = (char *) malloc(sizeof(char) * (length/2+1));
+        tableIndex[i] = 0;
+    }
+
+    index = 0;
+    while (index < length) {
+        for (int i = 0; i < numRows && index < length; i++)
+            table[i][tableIndex[i]++] = s[index++];
+        for (int i = numRows - 2; i > 0 && index < length; i--)
+            table[i][tableIndex[i]++] = s[index++];
+    }
+
+    index = 0;
+
+    for (int i = 0; i < numRows; i++) {
+        strncpy(zigzag + index, table[i], tableIndex[i]);
+        index += tableIndex[i];
+    }
+    zigzag[index] = '\0';
+    return zigzag;
+}
+
+void testConvert() {
+    char *p1 = "nhlvnsnklobqkfoifwsdzfgoueicotgearzqloawcbomgcwnyosztzoqdyutrbxsuzignicqkresvbgwravnzjdek";
+    char *p2 = "PAHNAPLSIIGYIR";
+    int res = strcmp(convert(p1, 41), p2);
+    printf("%d\n", res);
+
+    char *p21 = "Apalindromeisaword,phrase,number,orothersequenceofunitsthatcanbereadthesamewayineitherdirection,withgeneralallowancesforadjustmentstopunctuationandworddividers.";
+    char *p22 = "Aiosrhem,tseoihartaaeeriwgrlasasnoctaoieplnrmiaodprs,ubroohreunefnttacneedhsmwynihrieto,iheeaalwnefrdutettpntainnwrdvdr.adew,anereqcustbaeeitdcntnlocojmsuuoddis";
+    int res2 = strcmp(convert(p21, 3), p22);
+    printf("%d\n", res2);
+}