Submission #3392244

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Source Code Expand

#include <bits/stdc++.h>

int main() {
    int n, k;
    std::string s;
    std::cin >> n >> k >> s;
    if (n > k) {
        std::bitset<210000> b;
        // A -> 0, B -> 1
        for (auto i = 0; i < s.size(); i++) {
            b[i] = s[i] == 'B';
        }
        for (int i = 0; i < k; i++) {
            if (b[0]) {
                b >>= 1;
                b = ~b;
                b[n - 1] = false;
            } else {
                b[0] = true;
            }
        }
        for (int i = 0; i < n; i++) std::cout << (b[i] ? 'B' : 'A');
    } else {
        if (n % 2) {
            std::cout << ((n - k) % 2 ? 'B' : 'A');
            for (int i = 1; i < n; i++) std::cout << (i % 2 ? 'B' : 'A');
        } else {
            for (int i = 0; i < n; i++) std::cout << (i % 2 ? 'A' : 'B');
        }
    }
    std::cout << std::endl;

    return 0;
}

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