In the problem 103107G - Go? No, the following code works in C++17 (GCC 7-32)(330101327), but fails in C++20 (GCC 13-64)(330101365) and C++23 (GCC 14-64, msys2) (330101397).

The exit code shows STATUS_STACK_OVERFLOW, but according to this, there should be enough stack space. I wonder if I did anything wrong or there's some problem with C++20,23?

Any insights or assistance would be greatly appreciated.

Code:

#include<bits/stdc++.h>
using namespace std;

const int N = 2005;
char s[N][N];

int n,m;
inline int T(int x,int y){return x*m+y;}

int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};

int max_cc = -1000;

int low[N][N],dfn[N][N],tot;
void tarjan(int ux,int uy,bool is_root){
    low[ux][uy]=dfn[ux][uy]=++tot;
    int cnt = 0;
    int ch = 0;
    for(int k=0;k<4;k++){
        int vx=ux+dx[k],vy=uy+dy[k];
        if(vx<0||vx>=n||vy<0||vy>=m)continue;
        if(s[vx][vy]=='#')continue;
        
        if(!dfn[vx][vy]){
            tarjan(vx,vy,0);
            low[ux][uy]=min(low[ux][uy],low[vx][vy]);
            if(low[vx][vy]>=dfn[ux][uy])cnt++;
            ch++;
        }
        else{
            low[ux][uy]=min(low[ux][uy],dfn[vx][vy]);
        }
    }
    

    if(is_root) max_cc=max(max_cc,ch-1);
    else max_cc=max(max_cc,cnt);
}

int main(){
    ios::sync_with_stdio(0);cin.tie(0);
    
    cin>>n>>m;
    for(int i=0;i<n;i++)cin>>s[i];

    int all=0;
    for(int i=0;i<n;i++){
        for(int j=0;j<m;j++){
            if(s[i][j]!='.')continue;
            if(!dfn[i][j]){
                all++;
                tarjan(i,j,1);
            }
        }
    }
    
    cout << max_cc + all << '\n';

    return 0;
}