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###### tags: `Leetcode`

# 909. Snakes and Ladders

###### Link : https://leetcode.com/problems/snakes-and-ladders/description/

## 題目
回傳由起點走到終點的最短路徑
## 程式碼 I

class Solution {
public:
    int snakesAndLadders(vector<vector<int>>& board) {
        const int n = board.size(), end = pow(n, 2);
        vector<int> Board;
        Board.push_back(0);
        for(int i = n-1, j = 0;i >= 0;i--, j++){
            if(j & 1)
                Board.insert(Board.end(), board[i].rbegin(), board[i].rend());
            else
                Board.insert(Board.end(), board[i].begin(), board[i].end());
        }
        vector<int> dist(n * n + 1, -1);
        queue<int> Queue;
        dist[1] = 0;
        Queue.push(1);
        while(!Queue.empty()){
            int cur = Queue.front();
            Queue.pop();
            for(int j = 1;j <= 6;j++){
                if(cur + j > end) break;
                int dest = (Board[cur + j] == -1)?cur + j:Board[cur + j];
                if(dist[dest] == -1){
                    dist[dest] = dist[cur] + 1;
                    Queue.push(dest);
                }
            }
        }
        return dist[end];
    }
};

## Date
2023/1/24