Untitled

class Solution {
public:
    pair<int,int> cord(int n, int size) {
    int r = (n - 1) / size; // Subtract 1 from n to make it 0-based.
    int c = (n - 1) % size;
    // In the context of the game board, we subtract 1 from n to make it 0-based.
    // This assumes that square 1 is in the bottom-left corner of the board.
    // If square 1 is in the top-left corner, you can change the calculations accordingly.
    if (r % 2 == 1) {
        // If the row is odd, reverse the column.
        c = size - 1 - c;
    }
    r = size - 1 - r; // Reverse the row to match the board layout.
    return {r, c};
}

    int snakesAndLadders(vector<vector<int>>& board) {
        int size=board.size();
        queue<pair<int,int>> q;  // (square number , moves)
        unordered_set<int> vis;
        q.push({1,0});
        vis.insert(1);


        while(!q.empty()){
            int f=q.front().first;
            int moves=q.front().second;
            q.pop();
            if(f==size*size) return moves;

            for(int i=1;i<=6 && f+i<=size*size;i++){ //do the initial jump and then check if you have landed on ladder or snake
                int next =f+i; //initial jump
                //if(vis.count(next)) continue;
                pair<int,int> p = cord(next,size);
                int r=p.first ,c=p.second;

                if(board[r][c]!=-1){  //good landing
                    next=board[r][c];
                }
                if(!vis.count(next)){
                    q.push({next,moves+1});
                    vis.insert(next);
                }
            }
        }
        return -1;  
    }
};


/* 
if(vis.count(f+i)) continue;

                pair<int,int> p=cord(f+i,size);
                int r=p.first,c=p.second;
                if(f+i==size*size) return moves+1;
                if(board[r][c]!=-1){
                    if(board[r][c]==size*size) return moves+1;
                    q.push({board[r][c],moves+1});
                    vis.insert(board[r][c]);
                }else{
                    q.push({f+i,moves+1});
                    vis.insert(f+i);
                } */