solution: Sudoku Solver

Author: Kilerd

src/main.rs

@@ -28,6 +28,7 @@ mod sort_array_by_parity;
 mod sort_array_by_parity_ii;
 mod sort_colors;
 mod string_to_integer_atoi;
+mod sudoku_solver;
 mod three_sum;
 mod three_sum_closest;
 mod to_lower_case;

src/sudoku_solver.rs

@@ -0,0 +1,139 @@
+/// @number 37
+/// @title Sudoku Solver
+/// @url https://leetcode.com/problems/sudoku-solver/
+/// @difficulty Hard
+
+struct Solution;
+
+impl Solution {
+    pub fn solve_sudoku(board: &mut Vec<Vec<char>>) {
+        let mut empty_position = vec![];
+        for i in 0..9 {
+            for j in 0..9 {
+                if board[i][j] == '.' {
+                    empty_position.push((i, j));
+                    board[i][j] = '0';
+                }
+            }
+        }
+        let position_len = empty_position.len();
+
+        let mut loop_index = 0;
+        while loop_index < position_len {
+            let (x, y) = empty_position[loop_index];
+
+            if board[x][y] < '9' {
+                board[x][y] = std::char::from_u32((board[x][y] as u32) + 1).unwrap();
+            } else {
+                board[x][y] = '0';
+                loop_index -= 1;
+                continue;
+            }
+            if Solution::invalid(board, x, y) {
+                continue;
+            }
+            loop_index += 1;
+        }
+    }
+    pub fn invalid(board: &Vec<Vec<char>>, x: usize, y: usize) -> bool {
+        use std::collections::HashSet;
+        let mut contain_table = HashSet::new();
+
+        // validate line
+        for i in 0..9 {
+            let x1 = board[x][i];
+            if x1 != '0' {
+                if contain_table.contains(&x1) {
+                    return true;
+                }
+                contain_table.insert(x1);
+            }
+        }
+        contain_table.clear();
+
+        // validate column
+
+        for i in 0..9 {
+            let x2 = board[i][y];
+            if x2 != '0' {
+                if contain_table.contains(&x2) {
+                    return true;
+                }
+                contain_table.insert(x2);
+            }
+        }
+
+        contain_table.clear();
+        // validate box
+
+        let i1 = x / 3;
+        let i2 = y / 3;
+        for i in 0..3 {
+            for j in 0..3 {
+                let x3 = board[i1 * 3 + i][i2 * 3 + j];
+                if x3 != '0' {
+                    if contain_table.contains(&x3) {
+                        return true;
+                    }
+                    contain_table.insert(x3);
+                }
+            }
+        }
+        contain_table.clear();
+        false
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::sudoku_solver::Solution;
+
+    #[test]
+    fn test() {
+        let mut sudoku = vec![
+            vec!['5', '3', '.', '.', '7', '.', '.', '.', '.'],
+            vec!['6', '.', '.', '1', '9', '5', '.', '.', '.'],
+            vec!['.', '9', '8', '.', '.', '.', '.', '6', '.'],
+            vec!['8', '.', '.', '.', '6', '.', '.', '.', '3'],
+            vec!['4', '.', '.', '8', '.', '3', '.', '.', '1'],
+            vec!['7', '.', '.', '.', '2', '.', '.', '.', '6'],
+            vec!['.', '6', '.', '.', '.', '.', '2', '8', '.'],
+            vec!['.', '.', '.', '4', '1', '9', '.', '.', '5'],
+            vec!['.', '.', '.', '.', '8', '.', '.', '7', '9'],
+        ];
+        Solution::solve_sudoku(&mut sudoku);
+
+        let mut expected_solution = vec![
+            vec!['5', '3', '4', '6', '7', '8', '9', '1', '2'],
+            vec!['6', '7', '2', '1', '9', '5', '3', '4', '8'],
+            vec!['1', '9', '8', '3', '4', '2', '5', '6', '7'],
+            vec!['8', '5', '9', '7', '6', '1', '4', '2', '3'],
+            vec!['4', '2', '6', '8', '5', '3', '7', '9', '1'],
+            vec!['7', '1', '3', '9', '2', '4', '8', '5', '6'],
+            vec!['9', '6', '1', '5', '3', '7', '2', '8', '4'],
+            vec!['2', '8', '7', '4', '1', '9', '6', '3', '5'],
+            vec!['3', '4', '5', '2', '8', '6', '1', '7', '9'],
+        ];
+        assert_eq!(expected_solution, sudoku);
+    }
+
+    #[test]
+    fn test_invalid_method() {
+        let mut expected_solution = vec![
+            vec!['5', '3', '4', '6', '7', '8', '9', '1', '2'],
+            vec!['6', '7', '2', '1', '9', '5', '3', '4', '8'],
+            vec!['1', '9', '8', '3', '4', '2', '5', '6', '7'],
+            vec!['8', '5', '9', '7', '6', '1', '4', '2', '3'],
+            vec!['4', '2', '6', '8', '5', '3', '7', '9', '1'],
+            vec!['7', '1', '3', '9', '2', '4', '8', '5', '6'],
+            vec!['9', '6', '1', '5', '3', '7', '2', '8', '4'],
+            vec!['2', '8', '7', '4', '1', '9', '6', '3', '5'],
+            vec!['3', '4', '5', '2', '8', '6', '1', '7', '9'],
+        ];
+        for i in 0..9 {
+            for j in 0..9 {
+                assert_eq!(false, Solution::invalid(&expected_solution, i, j));
+            }
+        }
+    }
+}