Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
#define rep(i,n) for(int i=0;i<n;i++)
#define MAX_N (int)1e5

int N, K;
string S;
vector<pair<int, char>> a;

void solve(){
    a.emplace_back(make_pair(0, S[0]));
    for(int i=1;i<N;i++) {
        if(S[i] != S[i-1]){
            a.emplace_back(make_pair(i, S[i]));
        }
    }
    a.emplace_back(make_pair(N, S[N-1]));

    while(a.size()<3*K+1){
        a.emplace_back(make_pair(N, S[N-1]));
    }

    int MAX = 0;
    rep(i, max(a.size()-2*K, K)){
        if(a[i].second=='0'){
            MAX = max(MAX, a[i+2*K].first - a[i].first);
        }else if(a[i].second=='1'){
            MAX = max(MAX, a[i+2*K+1].first - a[i].first);
        }
    }
    printf("%d\n", MAX);
}

int main(){
    cin >> N >> K;
    cin >> S;    
    solve();
    // printf("%d\n", a.size());
    // rep(i, a.size()){
    //     printf("%d\n", a[i].first);
    // }
    return 0;
}

Compiler output:
a.cc: In function 'void solve()':
a.cc:26:15: error: no matching function for call to 'max(std::vector<std::pair<int, char> >::size_type, int&)'
   26 |     rep(i, max(a.size()-2*K, K)){
      |            ~~~^~~~~~~~~~~~~~~~~
a.cc:5:32: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(int i=0;i<n;i++)
      |                                ^
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:26:15: note:   deduced conflicting types for parameter 'const _Tp' ('long unsigned int' and 'int')
   26 |     rep(i, max(a.size()-2*K, K)){
      |            ~~~^~~~~~~~~~~~~~~~~
a.cc:5:32: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(int i=0;i<n;i++)
      |                                ^
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:26:15: note:   mismatched types 'std::initializer_list<_Tp>' and 'long unsigned int'
   26 |     rep(i, max(a.size()-2*K, K)){
      |            ~~~^~~~~~~~~~~~~~~~~
a.cc:5:32: note: in definition of macro 'rep'
    5 | #define rep(i,n) for(int i=0;i<n;i++)
      |                                ^