codeforces#297div2_b 贪心,字符串,哈希

codeforces#297div2_b 贪心,字符串

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 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 ≤ aiai ≤ |s|) — the position from which Pasha started transforming the string on thei-th day.

Output

In the first line of the output print what Pasha's string s will look like after m days.

Sample test(s)
input
abcdef
1
2
output
aedcbf
input
vwxyz
2
2 2
output
vwxyz
input
abcdef
3
1 2 3
output
fbdcea
题意:如题
思路:由于对每个字符,翻转两次等于没翻,因此统计每个字符的翻转次数,判断奇偶,一个一个翻,复杂度o(n+m)
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<string>

using namespace std;

const int maxn=1000100;
const int INF=(1<<29);
const double EPS=0.0000001;

string s;
int m,a;
int x[maxn];

int main()
{
    cin>>s>>m;
    memset(x,0,sizeof(x));
    while(m--){
        scanf("%d",&a);
        x[a]++;
        x[s.length()+1-a]++;
    }
    for(int i=1;i<=s.length()/2;i++) x[i]+=x[i-1];
    for(int i=1;i<=s.length()/2;i++){
        if(x[i]&1) swap(s[i-1],s[s.length()-i]);
    }
    cout<<s<<endl;
    return 0;
}
View Code
没有AC不了的题,只有不努力的ACMER!
原文地址:https://www.cnblogs.com/--560/p/4417259.html