Remove All Adjacent Duplicates In String

就是找到并且去除回文啊。。用stack检查

class Solution {
     public String removeDuplicates(String S) {
         Stack st = new Stack();
         for(int i = 0; i < S.length(); i++) {
             if(!st.empty() && S.charAt(i) == st.peek()) //find
                 st.pop();
             else
                 st.push(S.charAt(i));
         }
         StringBuffer sb = new StringBuffer();
         int n = st.size();
         for(int i = 0 ; i < n; i++) {
             sb.append(st.pop());
         }
         sb.reverse();
         return sb.toString();
     }
 }