Given an m x n grid of characters board and a string word, return true if word exists in the grid.
The word can be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or vertically neighboring. The same letter cell may not be used more than once.
Example 1:
Input: board = [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], word = "ABCCED" Output: true
Example 2:
Input: board = [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], word = "SEE" Output: true
Example 3:
Input: board = [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], word = "ABCB" Output: false
Constraints:
m == board.lengthn = board[i].length1 <= m, n <= 61 <= word.length <= 15boardandwordconsists of only lowercase and uppercase English letters.
Follow up: Could you use search pruning to make your solution faster with a larger board?
class Solution:
def exist(self, board: List[List[str]], word: str) -> bool:
def dfs(i: int, j: int, k: int) -> bool:
if k == len(word) - 1:
return board[i][j] == word[k]
if board[i][j] != word[k]:
return False
c = board[i][j]
board[i][j] = "0"
for a, b in pairwise((-1, 0, 1, 0, -1)):
x, y = i + a, j + b
ok = 0 <= x < m and 0 <= y < n and board[x][y] != "0"
if ok and dfs(x, y, k + 1):
return True
board[i][j] = c
return False
m, n = len(board), len(board[0])
return any(dfs(i, j, 0) for i in range(m) for j in range(n))class Solution {
private int m;
private int n;
private String word;
private char[][] board;
public boolean exist(char[][] board, String word) {
m = board.length;
n = board[0].length;
this.word = word;
this.board = board;
for (int i = 0; i < m; ++i) {
for (int j = 0; j < n; ++j) {
if (dfs(i, j, 0)) {
return true;
}
}
}
return false;
}
private boolean dfs(int i, int j, int k) {
if (k == word.length() - 1) {
return board[i][j] == word.charAt(k);
}
if (board[i][j] != word.charAt(k)) {
return false;
}
char c = board[i][j];
board[i][j] = '0';
int[] dirs = {-1, 0, 1, 0, -1};
for (int u = 0; u < 4; ++u) {
int x = i + dirs[u], y = j + dirs[u + 1];
if (x >= 0 && x < m && y >= 0 && y < n && board[x][y] != '0' && dfs(x, y, k + 1)) {
return true;
}
}
board[i][j] = c;
return false;
}
}class Solution {
public:
bool exist(vector<vector<char>>& board, string word) {
int m = board.size(), n = board[0].size();
int dirs[5] = {-1, 0, 1, 0, -1};
function<bool(int, int, int)> dfs = [&](int i, int j, int k) -> bool {
if (k == word.size() - 1) {
return board[i][j] == word[k];
}
if (board[i][j] != word[k]) {
return false;
}
char c = board[i][j];
board[i][j] = '0';
for (int u = 0; u < 4; ++u) {
int x = i + dirs[u], y = j + dirs[u + 1];
if (x >= 0 && x < m && y >= 0 && y < n && board[x][y] != '0' && dfs(x, y, k + 1)) {
return true;
}
}
board[i][j] = c;
return false;
};
for (int i = 0; i < m; ++i) {
for (int j = 0; j < n; ++j) {
if (dfs(i, j, 0)) {
return true;
}
}
}
return false;
}
};func exist(board [][]byte, word string) bool {
m, n := len(board), len(board[0])
var dfs func(int, int, int) bool
dfs = func(i, j, k int) bool {
if k == len(word)-1 {
return board[i][j] == word[k]
}
if board[i][j] != word[k] {
return false
}
dirs := [5]int{-1, 0, 1, 0, -1}
c := board[i][j]
board[i][j] = '0'
for u := 0; u < 4; u++ {
x, y := i+dirs[u], j+dirs[u+1]
if x >= 0 && x < m && y >= 0 && y < n && board[x][y] != '0' && dfs(x, y, k+1) {
return true
}
}
board[i][j] = c
return false
}
for i := 0; i < m; i++ {
for j := 0; j < n; j++ {
if dfs(i, j, 0) {
return true
}
}
}
return false
}function exist(board: string[][], word: string): boolean {
const [m, n] = [board.length, board[0].length];
const dirs = [-1, 0, 1, 0, -1];
const dfs = (i: number, j: number, k: number): boolean => {
if (k === word.length - 1) {
return board[i][j] === word[k];
}
if (board[i][j] !== word[k]) {
return false;
}
const c = board[i][j];
board[i][j] = '0';
for (let u = 0; u < 4; ++u) {
const [x, y] = [i + dirs[u], j + dirs[u + 1]];
const ok = x >= 0 && x < m && y >= 0 && y < n;
if (ok && board[x][y] !== '0' && dfs(x, y, k + 1)) {
return true;
}
}
board[i][j] = c;
return false;
};
for (let i = 0; i < m; ++i) {
for (let j = 0; j < n; ++j) {
if (dfs(i, j, 0)) {
return true;
}
}
}
return false;
}public class Solution {
private int m;
private int n;
private char[][] board;
private string word;
public bool Exist(char[][] board, string word) {
m = board.Length;
n = board[0].Length;
this.board = board;
this.word = word;
for (int i = 0; i < m; ++i) {
for (int j = 0; j < n; ++j) {
if (dfs(i, j, 0)) {
return true;
}
}
}
return false;
}
private bool dfs(int i, int j, int k) {
if (k == word.Length - 1) {
return board[i][j] == word[k];
}
if (board[i][j] != word[k]) {
return false;
}
char c = board[i][j];
board[i][j] = '0';
int[] dirs = { -1, 0, 1, 0, -1 };
for (int u = 0; u < 4; ++u) {
int x = i + dirs[u];
int y = j + dirs[u + 1];
if (x >= 0 && x < m && y >= 0 && y < n && board[x][y] != '0' && dfs(x, y, k + 1)) {
return true;
}
}
board[i][j] = c;
return false;
}
}impl Solution {
fn dfs(
i: usize,
j: usize,
c: usize,
word: &[u8],
board: &Vec<Vec<char>>,
vis: &mut Vec<Vec<bool>>,
) -> bool {
if board[i][j] as u8 != word[c] {
return false;
}
if c == word.len() - 1 {
return true;
}
vis[i][j] = true;
let dirs = [[-1, 0], [0, -1], [1, 0], [0, 1]];
for [x, y] in dirs.into_iter() {
let i = x + i as i32;
let j = y + j as i32;
if i < 0 || i == board.len() as i32 || j < 0 || j == board[0].len() as i32 {
continue;
}
let (i, j) = (i as usize, j as usize);
if !vis[i][j] && Self::dfs(i, j, c + 1, word, board, vis) {
return true;
}
}
vis[i][j] = false;
false
}
pub fn exist(board: Vec<Vec<char>>, word: String) -> bool {
let m = board.len();
let n = board[0].len();
let word = word.as_bytes();
let mut vis = vec![vec![false; n]; m];
for i in 0..m {
for j in 0..n {
if Self::dfs(i, j, 0, word, &board, &mut vis) {
return true;
}
}
}
false
}
}