【hot100-java】【单词搜索】
回溯
回溯可以使用DFS+剪枝解决
class Solution {public boolean exist(char[][] board, String word) {char[] words=word.toCharArray();for(int i=0;i<board.length;i++){for(int j=0;j<board[0].length;j++){if(dfs(board,words,i,j,0)) return true;}}return false;}boolean dfs(char[][]board,char[]word,int i,int j,int k){if(i>=board.length||i<0||j>=board[0].length||j<0||board[i][j]!=word[k]) return false;if(k==word.length-1)return true;board[i][j]='\0';boolean ret=dfs(board,word,i+1,j,k+1)||dfs(board,word,i-1,j,k+1)||dfs(board,word,i,j+1,k+1)||dfs(board,word,i,j-1,k+1);board[i][j]=word[k];return ret;}
} 