G面经Prepare: Longest All One Substring

give a string, all 1 or 0, we can flip a 0 to 1, find the longest 1 substring after the flipping

这是一个简单版本of LC 424 Longest Repeating Character Replacement

又是Window, 又是Two Pointers

Window还是采用每次都try to update left使得window valid, 每次都检查最大window

 package GooglePhone;

 public class LongestOneSubstr {

     public static int find2(String str) {
         if (str==null || str.length()==0) return 0;
         int l = 0, r = 0;
         int maxLen = 0;
         int countZero = 0;
         for (r=0; r<str.length(); r++) {
             if (str.charAt(r) == '0') countZero++;
             while (countZero > 1 && l < str.length()) {
                 if (str.charAt(l) == '0') countZero--;
                 l++;
             }
             maxLen = Math.max(r-l+1, maxLen);
         }
         return maxLen;
     }

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub
         System.out.println(find2("10111000010110111101101010101"));
     }

 }