Rikka with string

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 581    Accepted Submission(s): 227

Problem Description
As we know, Rikka is poor at math. Yuta is worrying about this situation, so he gives Rikka some math tasks to practice. There is one of them:

One day, Yuta got a string which contains n letters but Rikka lost it in accident. Now they want to recover the string. Yuta remembers that the string only contains lowercase letters and it is not a palindrome string. Unfortunately he cannot remember some letters. Can you help him recover the string?

It is too difficult for Rikka. Can you help her?

 
Input
This problem has multi test cases (no more than 20). For each test case, The first line contains a number n(1≤n≤1000). The next line contains an n-length string which only contains lowercase letters and ‘?’ – the place which Yuta is not sure.
 
Output
For each test cases print a n-length string – the string you come up with. In the case where more than one string exists, print the lexicographically first one. In the case where no such string exists, output “QwQ”.
 
Sample Input
5
a?bb?
3
aaa
 
Sample Output
aabba
QwQ
 
Source

 #include<stdio.h>
#include<string.h>
int cnt = ;
char st[ + ] ;
char rst [ + ] ;
int n , vis[ + ]; void rev (char s[ + ])
{
char tmp[ + ] ;
int k = , i ;
for (i = strlen (st) - ; i >= ; i-- , k ++) {
tmp[k] = st[i] ;
}
tmp[k] = '\0' ;
strcpy (s , tmp) ;
} int main ()
{
// freopen ("a.txt" , "r" , stdin ) ;
while (~ scanf ("%d" , &n)) {
getchar () ;
gets (st) ;
cnt = ;
for (int i = ; st[i] != '\0' ;i ++) {
if (st[i] == '?') {
vis[cnt ++] = i ;
st[i] = 'a' ;
}
}
int i ;
rev (rst) ;
if (strcmp (st , rst)== ) {
for (i = cnt - ; i >= ; i--) {
st[vis[i]] = 'b' ;
rev (rst) ;
if (strcmp (rst , st)!= ) {
break ;
}
st[vis[i]] = 'a' ;
}
if (i == - ) puts ("QwQ") ;
else puts (st) ;
}
else puts (st) ;
}
return ;
}
如果没有不是回文串的限制可以把所有的?都变成a,这样一定是字典序最小的。而现在有了回文串的限制,我们可以从小到大枚举最靠后的不在字符串正中心的问号选什么,其他的问号依然换成a,显然如果有解,这样一定可以得到字典序最小的解。注意特判没有问号以及问号在正中心的情况。
时间复杂度O(n)

hdu.5202.Rikka with string(贪心)的更多相关文章

  1. HDU 6086 Rikka with String

    Rikka with String http://acm.hdu.edu.cn/showproblem.php?pid=6086 题意: 求一个长度为2L的,包含所给定的n的串,并且满足非对称. 分析 ...

  2. HDU 6086 Rikka with String AC自动机 + DP

    Rikka with String Problem Description As we know, Rikka is poor at math. Yuta is worrying about this ...

  3. hdoj - 5202 Rikka with string (BestCoder Round #37 ($))

    http://acm.hdu.edu.cn/showproblem.php?pid=5202 字符串处理的题,要细心. 给定一个只包含小写字母和问号的字符串,让我们还原出本来的字符串,把问号替换成任意 ...

  4. hdu 6086 -- Rikka with String(AC自动机 + 状压DP)

    题目链接 Problem Description As we know, Rikka is poor at math. Yuta is worrying about this situation, s ...

  5. HDU 6086 Rikka with String ——(AC自动机 + DP)

    这是一个AC自动机+dp的问题,在中间的串的处理可以枚举中断点来插入自动机内来实现,具体参见代码. 在这题上不止为何一直MLE,一直找不到结果(lyf相同写法的代码消耗内存较少),还好考虑到这题节点应 ...

  6. HDU 5831 Rikka with Parenthesis II(六花与括号II)

    31 Rikka with Parenthesis II (六花与括号II) Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536 ...

  7. HDU 6093 - Rikka with Number | 2017 Multi-University Training Contest 5

    JAVA+大数搞了一遍- - 不是很麻烦- - /* HDU 6093 - Rikka with Number [ 进制转换,康托展开,大数 ] | 2017 Multi-University Tra ...

  8. HDU 5842 Lweb and String(Lweb与字符串)

    p.MsoNormal { margin: 0pt; margin-bottom: .0001pt; text-align: justify; font-family: Calibri; font-s ...

  9. 判断相同区间(lazy) 多校8 HDU 5828 Rikka with Sequence

    // 判断相同区间(lazy) 多校8 HDU 5828 Rikka with Sequence // 题意:三种操作,1增加值,2开根,3求和 // 思路:这题与HDU 4027 和HDU 5634 ...

随机推荐

  1. IE firefox 兼容性整理

    1.尽量用jquery操作. 2.jquery取值时要用准确的方法,attr(), val(), text(), html(). 例如: <span value="a"> ...

  2. 如何添加win10命令提示符字体,美化显示效果

    如图,win10命令提示符的字体真让人难受的要死,难道就不能改成好看一点的吗?笔者开始了停不下来的百度和Google 在查找了大量零碎或者过时的资料后,终于找到了一篇看起来还是很靠谱的文章: Quic ...

  3. js判断页面点击事件

    <input type="submit" name="sb1" id="sb1" onclick="queryclick() ...

  4. 浅谈分治算法在OI中的应用

    分治虽然是基本思想,但是OI中不会出裸分治让你一眼看出来,往往都是结合到找规律里面. 先来个简单的: 奇妙变换 (magic.pas/c/cpp) [问题描述]   为了奖励牛牛同学帮妈妈解决了大写中 ...

  5. [工具类]DataTable与泛型集合List互转

    写在前面 工作中经常遇到datatable与list,对于datatable而言操作起来不太方便.所以有的时候还是非常希望通过泛型集合来进行操作的.所以这里就封装了一个扩展类.也方便使用. 类 方法中 ...

  6. jquery.validate.js常用扩展函数

    $(function () { // 判断整数value是否等于0 jQuery.validator.addMethod("isIntEqZero", function (valu ...

  7. loaded the "XXXView" nib but the view outlet was not set 解决方案

    '-[UIViewController _loadViewFromNibNamed:bundle:] loaded the "XXXView" nib but the view o ...

  8. Missing message for key "err1" in bundle "(default bundle)" for locale zh_CN

    这个问题是: 你的使用了ApplicationResources_zh_CN.properties文件没有找到. 1.是struts-config.xml中的<message-resources ...

  9. Spring控制Hibernate的缓存机制ehcache

    首先在spring.xml中进入bean <prop key="hibernate.cache.use_second_level_cache">true</pro ...

  10. 【kAri OJ604】圣哲的树

    时间限制 1000 ms 内存限制 65536 KB 题目描述 果园大咖圣哲有12个棵树,其中有且仅有一个是有病的,有病的树比真的或轻或重,给出3次天平测量重量的结果,每次告知左侧和右侧的树各有哪几个 ...