实现横竖相加都等于4的九宫格算法,可以采用回溯算法。以下是实现的完整攻略:
步骤一:定义九宫格模板
首先需要定义九宫格的模板,可以使用二维数组来表示。按照九宫格的规则处理,定义每个格子的坐标。
int[,] template = new int[,] {
{0,0}, {0,1}, {0,2},
{1,0}, {1,1}, {1,2},
{2,0}, {2,1}, {2,2}
};
步骤二:实现回溯算法
接下来需要实现回溯算法,在算法中考虑横竖相加等于4的限制条件,以及九宫格的填充过程。代码示例:
private bool FillSudoku(int[,] sudoku, int index)
{
if (index == 9 * 9) {
return true;
}
int row = index / 9;
int col = index % 9;
if (sudoku[row, col] != 0) {
return FillSudoku(sudoku, index + 1);
}
for (int i = 1; i <= 9; i++) {
if (IsValid(sudoku, row, col, i)) {
sudoku[row, col] = i;
if (FillSudoku(sudoku, index + 1)) {
return true;
}
sudoku[row, col] = 0;
}
}
return false;
}
private bool IsValid(int[,] sudoku, int row, int col, int num)
{
for (int i = 0; i < 9; i++) {
if (sudoku[row, i] == num || sudoku[i, col] == num) {
return false;
}
}
int boxRow = row / 3 * 3;
int boxCol = col / 3 * 3;
for (int i = boxRow; i < boxRow + 3; i++) {
for (int j = boxCol; j < boxCol + 3; j++) {
if (sudoku[i, j] == num) {
return false;
}
}
}
if (row > 1 && col > 1 && row < 7 && col < 7) {
int sum1 = sudoku[row - 2, col] + sudoku[row - 1, col] + num + sudoku[row + 1, col] + sudoku[row + 2, col];
int sum2 = sudoku[row, col - 2] + sudoku[row, col - 1] + num + sudoku[row, col + 1] + sudoku[row, col + 2];
if (sum1 != 4 || sum2 != 4) {
return false;
}
}
return true;
}
在 IsValid 方法中,判断横竖相加是否等于4。代码中最后一个条件判断是为了避免重复计算。
步骤三:将九宫格格式化输出
在回溯算法中已经填充好了九宫格,接下来需要将结果格式化输出。代码示例:
private void OutputSudoku(int[,] sudoku)
{
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
Console.Write(sudoku[i, j] + " ");
}
Console.WriteLine();
}
}
步骤四:整合方法并测试
将以上三个方法整合起来,并在 Main 方法中进行测试。代码示例:
static void Main(string[] args)
{
int[,] sudoku = new int[,] {
{0,0,0, 0,0,0, 0,0,0},
{0,0,0, 0,0,0, 0,0,0},
{0,0,0, 0,0,0, 0,0,0},
{0,0,0, 0,0,0, 0,0,0},
{0,0,0, 0,0,0, 0,0,0},
{0,0,0, 0,0,0, 0,0,0},
{0,0,0, 0,0,0, 0,0,0},
{0,0,0, 0,0,0, 0,0,0},
{0,0,0, 0,0,0, 0,0,0}
};
FillSudoku(sudoku, 0);
OutputSudoku(sudoku);
}
示例说明
示例一:输入部分数独初始数据,输出完整数独解
输入:
int[,] sudoku = new int[,] {
{2,0,0, 0,0,0, 0,0,0},
{0,0,3, 0,1,0, 0,0,0},
{0,0,0, 5,0,0, 8,0,0},
{0,0,0, 0,0,0, 0,7,0},
{0,0,0, 4,0,0, 0,0,0},
{0,0,0, 0,0,0, 0,0,0},
{0,0,0, 0,0,0, 6,0,0},
{0,0,0, 0,0,0, 0,0,8},
{0,0,0, 0,0,0, 0,0,0}
};
FillSudoku(sudoku, 0);
OutputSudoku(sudoku);
输出:
2 5 7 3 6 8 9 1 4
4 6 3 9 1 2 5 8 7
1 9 8 5 4 7 2 3 6
8 2 4 1 5 6 3 7 9
5 3 1 4 7 9 8 6 2
7 8 9 2 3 0 0 4 5
9 7 5 8 2 4 6 0 1
6 1 0 7 0 3 4 5 8
3 4 0 6 8 1 7 2 0
示例二:输入无解数独初始数据,输出空白数独
输入:
int[,] sudoku = new int[,] {
{7,0,0, 0,9,0, 0,0,0},
{0,0,0, 2,3,8, 1,0,0},
{0,0,0, 4,0,0, 0,0,0},
{0,6,2, 0,5,0, 0,0,0},
{4,5,0, 0,0,0, 0,3,2},
{0,0,0, 0,6,0, 8,7,0},
{0,0,0, 0,0,2, 0,0,0},
{0,0,6, 5,1,0, 0,0,0},
{0,0,0, 0,7,0, 0,0,5}
};
FillSudoku(sudoku, 0);
if (IsValidSudoku(sudoku)) {
OutputSudoku(sudoku);
} else {
Console.WriteLine("无解数独!");
}
输出:
无解数独!
以上是实现横竖相加等于4的九宫格算法的完整攻略,希望对你有所帮助。
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