zoukankan      html  css  js  c++  java
  • (贪心)cf 486C

    C. Palindrome Transformation
    time limit per test
    1 second
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    Nam is playing with a string on his computer. The string consists of n lowercase English letters. It is meaningless, so Nam decided to make the string more beautiful, that is to make it be a palindrome by using 4 arrow keys: left, right, up, down.

    There is a cursor pointing at some symbol of the string. Suppose that cursor is at position i (1 ≤ i ≤ n, the string uses 1-based indexing) now. Left and right arrow keys are used to move cursor around the string. The string is cyclic, that means that when Nam presses left arrow key, the cursor will move to position i - 1 if i > 1 or to the end of the string (i. e. position n) otherwise. The same holds when he presses the right arrow key (if i = n, the cursor appears at the beginning of the string).

    When Nam presses up arrow key, the letter which the text cursor is pointing to will change to the next letter in English alphabet (assuming that alphabet is also cyclic, i. e. after 'z' follows 'a'). The same holds when he presses the down arrow key.

    Initially, the text cursor is at position p.

    Because Nam has a lot homework to do, he wants to complete this as fast as possible. Can you help him by calculating the minimum number of arrow keys presses to make the string to be a palindrome?

    Input

    The first line contains two space-separated integers n (1 ≤ n ≤ 105) and p (1 ≤ p ≤ n), the length of Nam's string and the initial position of the text cursor.

    The next line contains n lowercase characters of Nam's string.

    Output

    Print the minimum number of presses needed to change string into a palindrome.

    Sample test(s)
    input
    8 3
    aeabcaez
    output
    6
    Note

    A string is a palindrome if it reads the same forward or reversed.

    In the sample test, initial Nam's string is:  (cursor position is shown bold).

    In optimal solution, Nam may do 6 following steps:

    The result, , is now a palindrome.

    贪心,,写的真挫。。。可以去死了。。。

    #include<iostream>
    #include<cstdio>
    #include<cstring>
    #include<string>
    #include<cstdlib>
    #include<algorithm>
    #include<cmath>
    using namespace std;
    char s[100010];
    int p,n,sum;
    int main()
    {
          scanf("%d%d",&n,&p);
          scanf("%s",s);
          if(p>n/2) p=n-p;
          else p--;
          int xmax=p,xmin=p;
          for(int i=0;i<n/2;i++)
          {
                if(s[i]!=s[n-i-1])
                {
                      xmin=min(i,xmin);
                      sum+=min(abs(s[i]-s[n-i-1]),26-abs(s[i]-s[n-i-1]));
                      xmax=max(i,xmax);
                }
          }
          sum+=(xmax-xmin)+min(abs(p-xmax),abs(p-xmin));
          printf("%d
    ",sum);
          return 0;
    }
    

      

  • 相关阅读:
    add repository(仓库) EntityState状态
    添加 Attribute(属性)和Attribute的用法
    分部视图 Partial View
    MVC架构+ef 添加、删除、查询用户。。。
    首次接触 ef
    了解ASP.NET MVC的基本架构
    C# SqlParameter SqlCommand
    mysql命令行导出导入,附加数据库
    py03_变量
    py02_操作系统
  • 原文地址:https://www.cnblogs.com/a972290869/p/4242757.html
Copyright © 2011-2022 走看看