Go Java算法之单词搜索示例详解

class Solution {
    public boolean exist(char[][] board, String word) {
        if (board == null || board.length == 0) {
            return false;
        }
        boolean[][] visited = new boolean[board.length][board[0].length];
        char[] chars = word.toCharArray();
        for (int i = 0; i < board.length; i++) {
            for (int j = 0; j < board[0].length; j++) {
                if (existHelper(board, visited, chars, i, j, 0)) {
                    return true;
                }
            }
        }
        return false;
    }
    private boolean existHelper(char[][] board, boolean[][] visited, char[] chars, int row, int column, int index) {
        if (index == chars.length) {
            return true;
        }
        int[][] direction = new int[][]{
                {0, 1},
                {1, 0},
                {0, -1},
                {-1, 0}
        };
        if (row >= 0 && row < board.length &&
                column >= 0 && column < board[0].length &&
                board[row][column] == chars[index] &&
                !visited[row][column]) {
            visited[row][column] = true;
            for (int[] dir : direction) {
                int newX = row + dir[0];
                int newY = column + dir[1];
                if (existHelper(board, visited, chars, newX, newY, index + 1)) {
                    return true;
                }
            }
            visited[row][column] = false;
        }
        return false;
    }
}

func exist(board [][]byte, word string) bool {
	m, n := len(board), len(board[0])
	used := make([][]bool, m)
	for i := 0; i < m; i++ {
		used[i] = make([]bool, n)
	}
	var canFind func(r, c, i int) bool
	canFind = func(r, c, i int) bool {
		if i == len(word) {
			return true
		}
		if r < 0 || r >= m || c < 0 || c >= n {
			return false
		}
		if used[r][c] || board[r][c] != word[i] {
			return false
		}
		used[r][c] = true
		canFindRest := canFind(r+1, c, i+1) || canFind(r-1, c, i+1) ||
			canFind(r, c+1, i+1) || canFind(r, c-1, i+1)
		if canFindRest {
			return true
		} else {
			used[r][c] = false
			return false
		}
	}
	for i := 0; i < m; i++ {
		for j := 0; j < n; j++ {
			if board[i][j] == word[0] && canFind(i, j, 0) {
				return true
			}
		}
	}
	return false
}