om attached segment font-content"><div style="position: relative; overflow: hidden;"><p><span style="font-size: medium">给出一个由小写字母组成的字符串S，问有多少由小写字母<br />
构成的字条串S',满足<br />
1:|S|'=|S|<br />
2:S'[L..R]是回文串，当且仅当S[L..R]是回文串<br />
</span></p></div></div></div></div><div class="row"><div class="column"><h4 class="ui top attached block header">输入格式</h4><div class="ui bottom attached segment font-content"><div sty