同楼上dalao做法：
#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <cstdlib>
#include <bitset>
using namespace std;
const int N = 1e4 + 10;
typedef long long LL;
typedef LL ll;
//18446744073709551616 LL_MAX >
//1000000000000000000 N_MAX
ll n, t;
int x = 1;
// string Bin;
string str;
int main() {
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
cin >> n >> t;
cin >> str;
int mx = 1;
while(mx < n)
{
mx *= 2;
}
t %= mx;
for(int i = 0; i < t; i ++)
{
for(int j = n - 1; j >= 1; j --)
{
str[j] = ( str[j] - '0' ) ^ ( str[j - 1] - '0' ) + '0';
}
}
cout << str << '\n';
return 0;
}