message: Update read-n-characters-given-read4-ii-call-multiple-times.cpp
diff: // Forward declaration of the read4 API.
  int read4(char *buf);
  +// shorter version of Solution2
  class Solution {
  +public:
  + /**
  + * @param buf Destination buffer
  + * @param n Maximum number of characters to read
  + * @return The number of characters read
  + */
  + int read(char *buf, int n) {
  + int i = 0;
  + while (i < n && (i4_ < n4_ || (i4_ = 0) < (n4_ = read4(buf4_)))) {
  + buf[i++] = buf4_[i4_++];
  + }
  + return i;
  + }
  +
  +private:
  + char buf4_[4];
  + int i4_ = 0, n4_ = 0;
  +};
  +
  +// Time: O(n)
  +// Space: O(1)
  +class Solution2 {
  public:
  /**
  * @param buf Destination buffer
  