1003. 检查替换后的词是否有效

解法一

每次找字符串“abc”然后删除，直到找不到为止。如果此时字符串非空，则说明不满足题意。

class Solution {
    public boolean isValid(String S) {
        StringBuilder stringBuilder = new StringBuilder(S);
        String vaildString = "abc";
        int pos;
        while (true) {
            pos = stringBuilder.indexOf(vaildString);
            if (pos >= 0) {
                stringBuilder.delete(pos, pos + 3);
            } else {
                break;
            }
        }
        if (stringBuilder.length() > 0) {
            return false;
        } else {
            return true;
        }
    }
}