剑指 Offer 12. 矩阵中的路径

 func exist(_ board: [[Character]], _ word: String) -> Bool {
        
        let wordArray = Array(word)
        var tempArray = board

        for i in 0...tempArray.count - 1 {
            
            for j in 0...tempArray[0].count - 1 {
                
                if dfs(&tempArray, wordArray, i, j, 0) {
                    return true
                }
               
            }
            
            
        }
    
        
        
      return  false
    }
    
    
    func dfs(_ array: inout [[Character]],_ words:[Character],_ i:Int,_ j:Int,_ k: Int) -> Bool {
        
        if i >= array.count || j >= array[0].count || i < 0 || j < 0 || array[i][j] != words[k]{
            return false
        }
        if k == words.count - 1 {
            return true
        }
        
        array[i][j] = "\0"
        
        let res = dfs(&array, words, i + 1, j, k + 1) || dfs(&array, words, i - 1, j ,k + 1) || dfs(&array, words, i, j + 1, k + 1) || dfs(&array, words, i, j - 1, k + 1)
        
        array[i][j] = words[k]

        return res
        
    }