剑指 Offer 12. 矩阵中的路径

题目

剑指 Offer 12. 矩阵中的路径

代码

class Solution {
public:
    bool exist(vector<vector<char>>& board, string word) {
        for(int i =0; i < board.size(); i++)
            for(int j = 0; j < board[i].size(); j++)
                if(dfs(board, word, 0, i, j))
                    return true;
                return false;
    }

    bool dfs(vector<vector<char>>& board, string word, int n, int x, int y) {
        if(board[x][y] != word[n])  //当前字符串不匹配直接返回false
            return false;
        if(n == word.size() - 1)  //当前字符匹配且当前为最后一个字符时，直接返回true
            return true;
        int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};
        char t = board[x][y];
        board[x][y] = '*';
        for(int i = 0; i < 4; i++) {
            int a = x + dx[i], b = y + dy[i];
            if(a >= 0 && a < board.size() && b >= 0 && b < board[a].size())
                if(dfs(board, word, n + 1, a, b))
                    return true;
        }
        board[x][y] = t;
        return false;
    }
};