https://leetcode-cn.com/problems/word-search/

深度优先遍历 + 添加现场

public boolean exist(char[][] board, String word) {
    char[] w = word.toCharArray();
    for (int i = 0; i < board.length; i++) {
        for (int j = 0; j < board[0].length; j++) {
            if (process(board, i, j, w, 0)) {
                return true;
            }
        }
    }
    return false;
}
private boolean process(char[][] board, int i, int j, char[] w, int k) {
    if (k == w.length) {
        return true;
    }
    if (i < 0 || i == board.length || j < 0 || j == board[0].length) {
        return false;
    }
    if (w[k] != board[i][j]) {
        return false;
    }
    char tmp = board[i][j];
    //不走回头路机制  --> 增加现场
    board[i][j] = 0;
    boolean ans = process(board, i - 1, j, w, k + 1)
        || process(board, i + 1, j, w, k + 1)
        || process(board, i, j - 1, w, k + 1)
        || process(board, i, j + 1, w, k + 1);
    // 恢复现场
    board[i][j] = tmp;
    return ans;
}