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-rw-r--r--sudoku_solver.c69
-rw-r--r--sudoku_solver.py66
2 files changed, 135 insertions, 0 deletions
diff --git a/sudoku_solver.c b/sudoku_solver.c
new file mode 100644
index 0000000..88ccc01
--- /dev/null
+++ b/sudoku_solver.c
@@ -0,0 +1,69 @@
+// 37. Sudoku Solver
+#include "leetcode.h"
+
+/*
+ * write a program to solve a sudoku puzzle by filling the empty cells. a sudoku
+ * solution must satisfy all of the following rules. each of the digits '1-9'
+ * must occur exactly once in each row, each of the digits '1-9', must occur
+ * exactly once in each column, and each of the digits '1-9' must occur exactly
+ * once in each of the 9 3x3 sub-boxes of the grid. the '.' character indicates
+ * empty cells.
+ */
+
+bool solve(char **board, bool row[9][9], bool col[9][9], bool grid[9][9], int r,
+ int c) {
+ if (r == 9)
+ return true;
+ int next_r = c == 8 ? r + 1 : r;
+ int next_c = c == 8 ? 0 : c + 1;
+ if (board[r][c] != '.')
+ return solve(board, row, col, grid, next_r, next_c);
+ int grid_idx = (r / 3) * 3 + (c / 3);
+ for (int i = 0; i < 9; i++) {
+ if (!row[r][i] && !col[c][i] && !grid[grid_idx][i]) {
+ board[r][c] = '1' + i;
+ row[r][i] = col[c][i] = grid[grid_idx][i] = true;
+ if (solve(board, row, col, grid, next_r, next_c))
+ return true;
+ board[r][c] = '.';
+ row[r][i] = col[c][i] = grid[grid_idx][i] = false;
+ }
+ }
+ return false;
+}
+
+void solveSudoku(char **board, int boardSize, int *boardColSize) {
+ if (boardSize != 9 || *boardColSize != 9)
+ return;
+ bool row[9][9] = {false};
+ bool col[9][9] = {false};
+ bool grid[9][9] = {false};
+ for (int i = 0; i < 9; i++)
+ for (int j = 0; j < 9; j++)
+ if (board[i][j] != '.') {
+ int num = board[i][j] - '1';
+ if (num < 0 || num >= 9)
+ return;
+ row[i][num] = col[j][num] = true;
+ grid[(i / 3) * 3 + (j / 3)][num] = true;
+ }
+ solve(board, row, col, grid, 0, 0);
+}
+
+int main() {
+ char *board[] = {{"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"}};
+ solveSudoku((char **)board, ARRAY_SIZE(board), ARRAY_SIZE(board[0]));
+ for (int i = 0; i < ARRAY_SIZE(board); i++) {
+ for (int j = 0; j < ARRAY_SIZE(board[0]); j++)
+ printf("%c ", board[i][j]);
+ printf("\n");
+ }
+}
diff --git a/sudoku_solver.py b/sudoku_solver.py
new file mode 100644
index 0000000..7a395e7
--- /dev/null
+++ b/sudoku_solver.py
@@ -0,0 +1,66 @@
+# 37. Sudoku Solver
+
+"""
+write a program to solve a sudoku puzzle by filling the empty cells. a sudoku
+solution must satisfy all of the following rules. each of the digits '1-9'
+must occur exactly once in each row, each of the digits '1-9', must occur
+exactly once in each column, and each of the digits '1-9' must occur exactly
+once in each of the 9 3x3 sub-boxes of the grid. the '.' character indicates
+empty cells.
+"""
+
+
+class Solution(object):
+ def solveSudoku(self, board):
+ """
+ :type board: List[List[str]]
+ :rtype: None Do not return anything, modify board in-place instead.
+ """
+ n = 9
+
+ def valid(row, col, idx):
+ row, col = int(row), int(col)
+ for i in range(9):
+ if board[i][col] == idx:
+ return False
+ if board[row][i] == idx:
+ return False
+ if board[3 * (row // 3) + i // 3][3 * (col // 3) + i % 3] == idx:
+ return False
+ return True
+
+ def solve(row, col):
+ if row == n:
+ return True
+ if col == n:
+ return solve(row + 1, 0)
+ if board[row][col] == ".":
+ for i in range(1, 10):
+ if valid(row, col, str(i)):
+ board[row][col] = str(i)
+ if solve(row, col + 1):
+ return True
+ else:
+ board[row][col] = "."
+ return False
+ else:
+ return solve(row, col + 1)
+
+ solve(0, 0)
+
+
+if __name__ == "__main__":
+ obj = Solution()
+ board = [
+ ["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"],
+ ]
+ obj.solveSudoku(board)
+ print(board)