[LeetCode]Word Search-优快云博客

本文链接：https://blog.youkuaiyun.com/sunbaigui/article/details/8981378

本文介绍了一种使用C++实现的迷宫寻路算法，通过深度优先搜索（DFS）来查找给定字符矩阵中是否存在指定字符串路径。文章详细阐述了如何遍历二维字符数组并检查是否可以找到目标单词，同时提供了完整的代码示例。

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int Dir[4][2]={{0,1},{0,-1},{1,0},{-1,0}};
class Solution {
//DFS Find the path
public:
	
	void DFS(int curX, int curY, int curPos, vector<vector<bool>>& visit, 
		bool& OK, vector<vector<char>> &board, string& word )
	{
		if(OK) return;
		if(word[curPos] != board[curX][curY]) return;
		if(curPos == word.size()-1)
		{
			OK = true;
			return;
		}
		for (int d = 0; d < 4; ++d)
		{
			int nextX = curX+Dir[d][0];
			int nextY = curY+Dir[d][1];
			if(nextX >= 0 && nextX < board.size() && nextY >= 0 && nextY < board[0].size())
			{
				if(!visit[nextX][nextY])
				{
					visit[nextX][nextY] = true;
					DFS(nextX, nextY, curPos+1, visit, OK, board, word);
					visit[nextX][nextY] = false;
				}
			}

		}
	}
public:
	bool exist(vector<vector<char> > &board, string word) {
		// Start typing your C/C++ solution below
		// DO NOT write int main() function
		if(word.size() == 0) return false;
		if(board.size() == 0 || board[0].size() == 0) return false;
		bool OK = false;
		vector<vector<bool>> visit(board.size(), vector<bool>(board[0].size(), false));
		for (int i = 0; i < board.size(); ++i)
		{
			for (int j = 0; j < board[i].size(); ++j)
			{
				visit[i][j] = true;
				DFS(i, j, 0, visit, OK, board, word);
				visit[i][j] = false;
				if(OK) return true;
			}
		}
		
		return false;
	}
};

second time

class Solution {
public:
    int dir[4][2] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
    bool findPath(vector<vector<char> > &board, string& word, vector<vector<bool> >& used, int curX, int curY, int curIdx)
    {
        int n = board.size();
        int m = board[curX].size();
        if(curIdx == word.size()) return true;
        for(int k = 0; k < 4; ++k)
        {
            int newX = curX+dir[k][0];
            int newY = curY+dir[k][1];
            if(newX >= 0 && newX < n && newY >= 0 && newY < m && used[newX][newY] == false && board[newX][newY] == word[curIdx])
            {
                used[newX][newY] = true;
                if(findPath(board, word, used, newX, newY, curIdx+1)) return true;
                used[newX][newY] = false;
            }
        }
        return false;
    }
    bool exist(vector<vector<char> > &board, string word) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(word.size() == 0) return true;
        int n = board.size();
        if(n == 0) return false;
        int m = board[0].size();
        
        vector<vector<bool> > used(n, vector<bool>(n, false));
        for(int i = 0; i < board.size(); ++i)
        {
            for(int j = 0; j < board[i].size(); ++j)
            {
                if(board[i][j] == word[0])
                {
                    used[i][j] = true;
                    if(findPath(board, word, used, i, j, 1)) return true;
                    used[i][j] = false;
                }
            }
        }
        return false;
    }
};