DqD2OH - Online C++ Compiler & Debugging Tool

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

int n, m, a[1005][1005];

int BFS() {
    int M[1005][1005] = {};
    queue<pair<int, int>> q;
    q.push({1, 1});
    M[1][1] = 0;

    while (!q.empty()) {
        auto [x, y] = q.front(); q.pop();

        if (x + a[x][y] <= n && !M[x + a[x][y]][y]) {
            if (x + a[x][y] == n && y == m) return M[x][y] + 1;
            M[x + a[x][y]][y] = M[x][y] + 1;
            q.push({x + a[x][y], y});
        }

        if (y + a[x][y] <= m && !M[x][y + a[x][y]]) {
            if (x == n && y + a[x][y] == m) return M[x][y] + 1;
            M[x][y + a[x][y]] = M[x][y] + 1;
            q.push({x, y + a[x][y]});
        }
    }
    return -1;
}

int main() {
    ios::sync_with_stdio(false); cin.tie(0);
    int t; cin >> t;
    while (t--) {
        cin >> n >> m;
        for (int i = 1; i <= n; ++i)
            for (int j = 1; j <= m; ++j)
                cin >> a[i][j];
        cout << BFS() << '\n';
    }
    return 0;
}