给S,T两个串，可以无限次选择在S串里一个字符后面添加一个字符，但是添加的这个字符不能和选择的字符相同，问S串能不能变成T串。



思路：



经过观察发现，如果S和T长度一样直接判。



如果不一样的话，只要满足



1、S里面的所有字符的顺序都在T串里出现过



2、T前面相同的字符和S的前部分能匹配



这里两个条件，就能构成。-To the S, T two strings, you can choose to add an unlimited number of S in a string of characters behind a character, but with the addition of this character can not choose the same character, ask S series can become T string.



Ideas:



After observed that if S and T as the length of the direct negotiations.



If you do not like it, as long as



1, the order of all the characters inside S appear in the T series in over



2, the front part of the same character in front of T and S can match



Here two conditions can be constituted.