Codeforces Round #297 (Div. 2)B. Pasha and String
Time Limit: 2 Sec Memory Limit: 256 MB
Submit: xxx Solved: 2xx
题目连接
http://codeforces.com/contest/525/problem/B
Description
Pasha got a very beautiful string s for his birthday, the string consists of lowercase Latin letters. The letters in the string are numbered from 1 to |s| from left to right, where |s| is the length of the given string.
Pasha didn't like his present very much so he decided to change it. After his birthday Pasha spent m days performing the following transformations on his string — each day he chose integer ai and reversed a piece of string (a segment) from position ai to position |s| - ai + 1. It is guaranteed that 2·ai ≤ |s|.
You face the following task: determine what Pasha's string will look like after m days.
Input
The first line of the input contains Pasha's string s of length from 2 to 2·105 characters, consisting of lowercase Latin letters.
The second line contains a single integer m (1 ≤ m ≤ 105) — the number of days when Pasha changed his string.
The third line contains m space-separated elements ai (1 ≤ ai; 2·ai ≤ |s|) — the position from which Pasha started transforming the string on the i-th day.
Output
Sample Input
abcdef
1
2
vwxyz
2
2 2
abcdef
3
1 2 3
Sample Output
aedcbf
vwxyz
fbdcea
HINT
题意:
给你一个字符串,然后给你一个数字i,然后i到s.size()-i直接的位置全部翻转,然后问你m次操作之后,是什么样子
题解:
首先,只有翻转奇数次和翻转偶数次两种情况,我们用一个类似前缀和的操作,就可以处理出这个位置究竟翻转了多少次,然后输出就好啦
~\(≧▽≦)/~啦啦啦,这道题完啦
代码:
//qscqesze
#include <cstdio>
#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <sstream>
#include <queue>
#include <typeinfo>
#include <fstream>
#include <map>
typedef long long ll;
using namespace std;
//freopen("D.in","r",stdin);
//freopen("D.out","w",stdout);
#define sspeed ios_base::sync_with_stdio(0);cin.tie(0)
#define maxn 400010
#define mod 10007
#define eps 1e-9
//const int inf=0x7fffffff; //无限大
const int inf=0x3f3f3f3f;
/* */
//**************************************************************************************
inline ll read()
{
int x=,f=;char ch=getchar();
while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}
while(ch>=''&&ch<=''){x=x*+ch-'';ch=getchar();}
return x*f;
}
int flag[maxn];
int main()
{
string s;
cin>>s;
int n;
cin>>n;
for(int i=;i<n;i++)
{
int x=read();
flag[x-]++;
}
for(int i=;i<=s.size()/;i++)
{
flag[i]+=flag[i-];
}
for(int i=;i<s.size();i++)
{
if(i<s.size()/)
{
if(flag[i]%==)
cout<<s[i];
else
cout<<s[s.size()-i-];
}
else
{
if(flag[s.size()-i-]%==)
cout<<s[i];
else
cout<<s[s.size()-i-];
}
}
}