ReverseInteger

Refine ReverseInteger solution so that it can pass all test cases.

Author: mengli

ReverseInteger.java

@@ -21,16 +21,16 @@
 
 public class ReverseInteger {
 	public int reverse(int x) {
-		int num = Math.abs(x);
-		int ret = 0;
+		long num = Math.abs(x);
+		long ret = 0;
 		while (num != 0) {
 			int d = num - num / 10 * 10;
 			ret = ret * 10 + d;
 			num /= 10;
 		}
 		if (x < 0)
-			return -ret;
+			return -ret < -2147483648 ? 0 : -ret;
 		else
-			return ret;
+			return ret > 2147483647 ? 0 : ret;
 	}
 }

ZigZagConversion.java

@@ -22,10 +22,11 @@ public String convert(String s, int numRows) {
         if (numRows <= 1) {
             return s;
         }
-		// Row index of each char in ZigZag form
+        // Row index of each char in ZigZag form
         int[] rowIndex = new int[s.length()];
         int row = -1;
-        boolean down = true; // Simlate the movement of ZigZag, up or down
+        // Simlate the movement of ZigZag, up or down
+        boolean down = true;
         for (int i = 0; i < rowIndex.length; i++) {
             if (down) {
                 row += 1;