题目比较简单，回溯最基础的题，记得除非覆盖，否则一定要恢复现场就行

解法都在代码里，不懂就留言或者私信

class Solution {public boolean exist(char[][] board, String word) {int m = board.length; int n = board[0].length;if(m * n < word.length()) {return false;}/**转换成字符数组 */char[] wordArr = word.toCharArray();for(int i = 0; i < board.length; i++) {for(int j = 0; j < board[i].length; j++) {/**任何一个成功，直接返回,这里加一下等于判断提高效率*/if(process(board, wordArr, i , j, 0)) {return true;}}}return false;}public boolean process(char[][] board, char[] wordArr, int row, int col, int curIndex) {if(curIndex == wordArr.length) {return true;}if(row < 0 || row >= board.length || col < 0 || col >= board[row].length || board[row][col] != wordArr[curIndex]) {return false;}/**用过的标记成0(数字0)并在此之前记录原始值，用于失败后的恢复现场*/char orginChar = board[row][col];board[row][col] = '0';/**上下左右都试一下 */boolean up = process(board, wordArr, row - 1, col, curIndex + 1);boolean right = process(board, wordArr, row, col + 1, curIndex + 1);boolean down = process(board, wordArr, row + 1, col, curIndex + 1);boolean left = process(board, wordArr, row, col - 1, curIndex + 1);/**任何一个成功就是成功，不再继续尝试 */if(up || right || down || left) {return true;}/**如果失败了下个需要重新从这个位置开始尝试，这里要恢复现场 */board[row][col] = orginChar;/**失败了返回false */return false;}
}