Leetcode-1003 Check If Word Is Valid After Substitutions(检查替换后的词是否有效)

 1 class Solution
 2 {
 3     public:
 4         bool isValid(string S)
 5         {
 6             if(S.size()%3!=0||S[0]!=‘a‘)
 7                 return false;
 8             int times = 6900;
 9             int presize = S.size();
10             while(S.size() && times--)
11             {
12                 for(int i = 0;i < S.size()-2;i ++)
13                 {
14                     if(S[i]==‘a‘&&S[i+1]==‘b‘&&S[i+2]==‘c‘)
15                     {
16                         S.erase(i,3);
17                         break;
18                     }
19                 }
20                 if(S.size()==presize)
21                     break;
22             }
23             return S.size()==0;
24         }
25 };