added more annotations and trailing newline

Author: rustykitty

0009-palindrome-number.cpp

@@ -12,8 +12,8 @@ class Solution {
     bool isPalindrome(int x) {
         if (x < 0) return false;
         // Reverse digits
-        long y = 0;
-        int x2 = x;
+        long y = 0; // we have to use a long because some inputs 
+        int x2 = x; // exceed 2^31-1 when reversed
         while (x2 != 0) {
             y *= 10;
             y += x2 % 10;

0014-longest-common-prefix.c

@@ -22,7 +22,7 @@ char* longestCommonPrefix(char** strs, int strsSize) {
     for (unsigned char i = 0; i < len_shortest; i++) {
         for (char** p = strs; p != strsEnd; ++p ) {
             char* str = *p;
-            // this means that the prefix ends here
+            // not equal, prefix ends here
             if (str[i] != strs[0][i]) return prefix;
         }
         prefix[i] = strs[0][i];