Update 006_ZigZag_conversion.java (#77)

* Update 006_ZigZag_conversion.java

Contributed by @green-study

Author: green-study

java/006_ZigZag_Conversion.java

@@ -1 +1,33 @@
-//TODO
+//006_ZigZag_Conversion.java
+class Solution {
+    public String convert(String s, int numRows) {
+        if(numRows==1) {
+            return s;
+        }
+
+        String answer = "";
+        String[] str_array = new String[numRows];
+
+        for(int i=0;i<numRows;i++){
+            str_array[i]="";
+        }
+
+        int mod = 2*numRows-2;
+
+        for(int i=0;i<s.length();i++){
+            char c = s.charAt(i);
+            int index = i%mod;
+            if(index >= numRows) {
+                index = 2*(numRows-1) - index;
+            }
+            str_array[index]+=c;
+        }
+
+        for(int i=0;i<numRows;i++){
+            answer += str_array[i];
+        }
+
+        return answer;
+    }
+}
+