題目:
題目描述:
判斷乙個 9x9 的數獨是否有效。只需要根據以下規則,驗證已經填入的數字是否有效即可。
數字1-9
在每一行只能出現一次。
數字1-9
在每一列只能出現一次。
數字1-9
在每乙個以粗實線分隔的3x3
宮內只能出現一次。
上圖是乙個部分填充的有效的數獨。
數獨部分空格內已填入了數字,空白格用'.'
表示。
示例 1:
輸入:
[ ["5","3",".",".","7",".",".",".","."],
["6",".",".","1","9","5",".",".","."],
[".","9","8",".",".",".",".","6","."],
["8",".",".",".","6",".",".",".","3"],
["4",".",".","8",".","3",".",".","1"],
["7",".",".",".","2",".",".",".","6"],
[".","6",".",".",".",".","2","8","."],
[".",".",".","4","1","9",".",".","5"],
[".",".",".",".","8",".",".","7","9"]
]輸出: true
示例 2:
輸入:
[ ["8","3",".",".","7",".",".",".","."],
["6",".",".","1","9","5",".",".","."],
[".","9","8",".",".",".",".","6","."],
["8",".",".",".","6",".",".",".","3"],
["4",".",".","8",".","3",".",".","1"],
["7",".",".",".","2",".",".",".","6"],
[".","6",".",".",".",".","2","8","."],
[".",".",".","4","1","9",".",".","5"],
[".",".",".",".","8",".",".","7","9"]
]輸出: false
解釋: 除了第一行的第乙個數字從 5 改為 8 以外,空格內其他數字均與 示例1 相同。
但由於位於左上角的 3x3 宮內有兩個 8 存在, 因此這個數獨是無效的。
說明:思路:這道題自己想沒想到,想過兩個for迴圈 暴力破解 時間複雜度o(n^2);看了下別人的思路。用二維boolean型陣列來作三個狀態表:分別是行表、列表、九宮格表。int index=i/3*3+j/3 這個公式能算出 board[i][j]所在的九宮格。
都用第乙個下標作為 位置標緻。
markrow[i] [ temp ] 從0到8表示棋盤的九行。
markrow[j] [ temp ] 的 i 表示 0到8列。
markblock[index] [ temp ] 的i 表示0到8號九宮格。
注意:布林陣列初始化值為false.
所以該錶開始都是false表示該位置為空。知道檢索到temp一次之後 ,將該位置設為true。如果同乙個i或j或者index 遇到過同乙個temp兩次表示數獨有問題,將該位置的指改為true ,返回false。
**:
class solution
}return true;
}
}
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