[LeetCode] 10. Regular Expression Matching

Implement regular expression matching with support for '.' and '*'.

DP:

 public class Solution {
     public boolean isMatch2(String s, String p) {
         int starCnt = 0;
         for (int i = 0; i < p.length(); i++) {
             if (p.charAt(i) == '*') {
                 starCnt++;
             }
         }

         boolean[] star = new boolean[p.length() - starCnt];
         StringBuilder temp = new StringBuilder(p.length() - starCnt);
         int index = -1;
         for (int i = 0; i < p.length(); i++) {
             if (p.charAt(i) == '*') {
                 star[index] = true;
             } else {
                 temp.append(p.charAt(i));
                 star[++index] = false;
             }
         }
         String r = temp.toString();

         boolean[] lastRow = new boolean[s.length() + 1];
         boolean[] curRow = new boolean[s.length() + 1];
         boolean[] tempRow;

         lastRow[0] = true;
         for (int i = 0; i < r.length(); i++) {
             if (star[i] && lastRow[0]) {
                 curRow[0] = true;
             } else {
                 curRow[0] = false;
             }

             for (int j = 0; j < s.length(); j++) {
                 if (!star[i]) {
                     if ((r.charAt(i) == '.' || r.charAt(i) == s.charAt(j)) && lastRow[j]) {
                         curRow[j + 1] = true;
                     } else {
                         curRow[j + 1] = false;
                     }
                 } else {
                     if (lastRow[j + 1]) {
                         curRow[j + 1] = true;
                     } else if (lastRow[j] || curRow[j]) {
                         if (r.charAt(i) == '.' || r.charAt(i) == s.charAt(j)) {
                             curRow[j + 1] = true;
                         } else {
                             curRow[j + 1] = false;
                         }
                     } else {
                         curRow[j + 1] = false;
                     }
                 }
             }

             tempRow = lastRow;
             lastRow = curRow;
             curRow = tempRow;
         }

         return lastRow[lastRow.length - 1];
     }
 }