B. Queue at the School

time limit per test2 seconds

memory limit per test256 megabytes

inputstandard input

outputstandard output

During the break the schoolchildren, boys and girls, formed a queue of n people in the canteen. Initially the children stood in the order they entered the canteen. However, after a while the boys started feeling awkward for standing in front of the girls in the queue and they started letting the girls move forward each second.

Let's describe the process more precisely. Let's say that the positions in the queue are sequentially numbered by integers from 1 to n, at that the person in the position number 1 is served first. Then, if at time x a boy stands on the i-th position and a girl stands on the (i + 1)-th position, then at time x + 1 the i-th position will have a girl and the (i + 1)-th position will have a boy. The time is given in seconds.

You've got the initial position of the children, at the initial moment of time. Determine the way the queue is going to look after t seconds.

Input

The first line contains two integers n and t (1 ≤ n, t ≤ 50), which represent the number of children in the queue and the time after which the queue will transform into the arrangement you need to find.

The next line contains string s, which represents the schoolchildren's initial arrangement. If the i-th position in the queue contains a boy, then the i-th character of string s equals "B", otherwise the i-th character equals "G".

Output

Print string a, which describes the arrangement after t seconds. If the i-th position has a boy after the needed time, then the i-th character a must equal "B", otherwise it must equal "G".

 

译文

学校排队

时间限制：2 秒

内存限制：256 MB

输入：标准输入

输出：标准输出

课间休息时，男女学生在食堂排起了 n 人的长队。起初，他们按照进入食堂的顺序站好。然而，过了一会儿，男生开始觉得站在女生前面很尴尬，于是他们开始让女生每秒钟向前移动一次。

让我们更精确地描述一下这个过程。假设队列中的位置按 1 到 n 的整数顺序编号，1 号位置上的人先得到服务。那么，如果在第 x 秒时，第 i 个位置上站着一个男孩，第 (i + 1) 个位置上站着一个女孩，那么在第 x + 1 秒时，第 i 个位置上将站着一个女孩，第 (i + 1) 个位置上将站着一个男孩。

你已经得到了学生们在初始时刻的初始位置。确定 t 秒后队列的样子。

输入

第一行包含两个整数 n 和 t（1 ≤ n，t ≤ 50），分别表示队列中的人数和队列转变为所需排列的时间。

下一行包含字符串 s，它代表学生的初始排列。如果队列中的第 i 个位置是男孩，则字符串 s 的对应第 i 个字符等于“B”，否则第 i 个字符等于“G”。

输出

打印字符串 a，表示 t 秒后队列的样子。如果第 i 个位置在 t 秒后是一个男孩，则第 i 个字符必须为 "B"，否则为 "G"。

 

样例

---

输入

5 1

BGGBG

输出

GBGGB

---

输入

5 2

BGGBG

输出

GGBGB

---

输入

4 1

GGGB

输出

GGGB

---

 

题解

#include <bits/stdc++.h>
using namespace std;
int n, t;
string s;
int main()
{
    cin >> n >> t >> s;
    // 需要同时将当前这一秒的所有BG全部改为GB
    while (t--)
    {
        for (int i = 0; i < s.size();)
        {
            if (s[i] == 'B' && s[i + 1] == 'G')
                swap(s[i], s[i + 1]), i += 2;
            else
                i += 1;
        }
    }
    cout << s;
    return 0;
}