ZigZag Conversion

Author: bap2pecs0

LeetCode/ZigZagConversion.py

@@ -0,0 +1,41 @@
+'''
+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
+And then read line by line: "PAHNAPLSIIGYIR"
+Write the code that will take a string and make this conversion given a number of rows:
+
+string convert(string text, int nRows);
+convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR".
+'''
+class Solution(object):
+    def convert(self, s, numRows):
+        if numRows == 1:
+            return s
+        
+        n = 2*numRows-2
+        result = ''
+        l = len(s)
+        
+        # the first row
+        for i in xrange(0, l, n):
+            result += s[i]
+        
+        # rows in between
+        for i in xrange(1,numRows-1):
+            j = i
+            while j < l+i-(n-i):
+                result += s[j]
+                result += s[j+(n-i)-i]
+                j += n
+            # if the number of chars in this row is odd
+            if j < l:
+                result += s[j]
+
+        # the last row
+        for i in xrange(numRows - 1, l, n):
+            result += s[i]
+            
+        return result