Thin Ice

input/code.cpp: In lambda function:
input/code.cpp:55:35: sorry, unimplemented: capture of variably-modified type 'int [(n + 1)][(m + 1)]' that is not an N3639 array of runtime bound
   55 |                 if (cur.sum + 1 > d[x][y]) continue;
      |                                   ^
input/code.cpp:55:35: note: because the array element type 'int [(m + 1)]' has variable size

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;

struct node{
    int x, y, sum;
    node(int i, int j){
        x = i; y = j; sum = 0;
    }
    map<pii, bool> mp;
};

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    int n, m; cin>>n>>m;
    int d[n + 1][m + 1];
    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= m; j++){
            cin>>d[i][j];
        }
    }
    auto adj = [&](int i, int j){
        vector<pii> out;
        if (i > 1){
            out.push_back({i - 1, j});
        }
        if (j > 1){
            out.push_back({i, j - 1});
        }
        if (i < n){
            out.push_back({i + 1, j});
        }
        if (j < m){
            out.push_back({i, j + 1});
        }
        return out;
    };
    auto solve = [&](int i, int j){
        queue<node> q;
        node st(i, j);
        q.push(st);
        int out = 0;
        while (!q.empty()){
            node cur = q.front(); q.pop();
            // cout<<cur.x<<" "<<cur.y<<"\n";
            if (cur.x == 1 || cur.x == n || cur.y == 1 || cur.y == m){
                out = max(out, cur.sum);
            }
            for (auto [x, y]: adj(cur.x, cur.y)){
                if (x > n || y > m || x < 1 || y < 1) continue;
                if (cur.sum + 1 > d[x][y]) continue;
                node nw = cur;
                nw.x = x;
                nw.y = y;
                nw.sum++;
                nw.mp[{x, y}] = true;
                q.push(nw);
            }
        }
        return out;
    };
    int out = 0;
    for (int i = 1; i <= n; i++){
        out = max(out, solve(i, 1));
        out = max(out, solve(i, m));
    }
    for (int j = 1; j <= m; j++){
        out = max(out, solve(1, j));
        out = max(out, solve(n, j));
    }
    cout<<out;
}