---
layout: page
title:  Word Search
last_solved: 2020-06-01
category: matrix
leetcode_url: https://leetcode.com/problems/word-search/
status: Attempted
---

##### Problem

{% highlight text %}

board =
[
  ['A','B','C','E'],
  ['S','F','C','S'],
  ['A','D','E','E']
]

Given word = "ABCCED", return true.
Given word = "SEE", return true.
Given word = "ABCB", return false.

{% endhighlight %}

##### Solution

tmp is to prevent going back and visiting an already visited cell

{% highlight python %}

def exist(board, word):

    R = len(board)
    C = len(board[0])

    def searchWord(i, j, word, index):

      if index==len(word):
        return True

      if i<0 or i>=R or j<0 or j>=C or board[i][j]!=word[index]:
        return False

      tmp = board[i][j]
      board[i][j] = ' '
      # found = searchWord(i+1,j,word,index+1)
      found = searchWord(i-1,j,word,index+1) or \
        searchWord(i+1,j,word,index+1) or \
        searchWord(i,j-1,word,index+1) or \
        searchWord(i,j+1,word,index + 1)

      board[i][j] = tmp
      return found

    for i in range(R):
      for j in range(C):
        if board[i][j]==word[0] and searchWord(i,j,word,0):
          return True

    return False

{% endhighlight %}


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