From 9bdedfa9d768668c571d721d0b7a30f0eae1b58c Mon Sep 17 00:00:00 2001 From: Jack Sangdahl Date: Fri, 29 Aug 2025 22:19:11 -0600 Subject: 36. valid sudoku --- valid_sudoku.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 valid_sudoku.c (limited to 'valid_sudoku.c') diff --git a/valid_sudoku.c b/valid_sudoku.c new file mode 100644 index 0000000..dd93f60 --- /dev/null +++ b/valid_sudoku.c @@ -0,0 +1,55 @@ +// 36. Valid Sudoku +#include "leetcode.h" + +/* + * determine if a 9 x 9 sudoku board is valid. only the filled cells need to be + * validated acording to the following rules. each row must contain the digits + * 1-9 without repetition, each column must contain the digits 1-9 without + * reptition, each of the nine 3 x 3 sub-boxes of the grid must contain the + * digits 1-9 without reptition. note, a sudoku board (partially filled) could + * be valid but it is not necessarily solvable. only the filled cells need to be + * validated according to the mentioned rules. + */ + +bool isValidSudoku(char **board, int boardSize, int *boardColSize) { + bool rows[9][9] = {false}; + bool cols[9][9] = {false}; + bool boxes[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'; + int box_idx = (i / 3) * 3 * (j / 3); + if (rows[i][num] || cols[j][num] || boxes[box_idx][num]) + return false; + rows[i][num] = cols[j][num] = boxes[box_idx][num] = true; + } + } + } + return true; +} + +int main() { + char *b1[] = {{"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"}}; + char *b2[] = {{"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"}}; + printf("%d\n", + isValidSudoku(b1, ARRAY_SIZE(b1), ARRAY_SIZE(b1[0]))); // expect: 1 + printf("%d\n", + isValidSudoku(b2, ARRAY_SIZE(b2), ARRAY_SIZE(b2[0]))); // expect: 0 +} -- cgit v1.2.3