Snake Ladder Problem!

• Time : $O(v)$
• Space : $O(v + snake + ladder)$

int Solution::snakeLadder(vector<vector<int>> &A, vector<vector<int>> &B) {
    vector<int> vis(101, -1);
    queue<int> q;
    q.push(1);
    vis[0] = vis[1] = 0;
    unordered_map<int, int> mp;
    for(auto vec : A) mp[vec[0]] = vec[1];
    for(auto vec : B) mp[vec[0]] = vec[1];
    while(q.size()) {
        auto u = q.front(); q.pop();
        for(int i = 1; i <= 6; i++) {
            if(u + i > 100 or vis[u + i] != -1) continue;
            vis[u + i] = vis[u] + 1;
            if(mp.count(u + i)) {
                if(vis[mp[u + i]] == -1) {
                    q.push(mp[u + i]);
                    vis[mp[u + i]] = vis[u] + 1;
                }
            } else q.push(u + i);
        }
    }

    return vis[100];
}