1958. Check if Move is Legal: RETRY, credit: https://leetcode.com/problems/check-if-move-is-legal/solutions/3241963/just-a-runnable-solution/

Author: tan-wei

Diff for: src/solution/mod.rs

@@ -1475,3 +1475,4 @@ mod s1953_maximum_number_of_weeks_for_which_you_can_work;
 mod s1954_minimum_garden_perimeter_to_collect_enough_apples;
 mod s1955_count_number_of_special_subsequences;
 mod s1957_delete_characters_to_make_fancy_string;
+mod s1958_check_if_move_is_legal;

Diff for: src/solution/s1958_check_if_move_is_legal.rs

@@ -0,0 +1,113 @@
+/**
+ * [1958] Check if Move is Legal
+ *
+ * You are given a 0-indexed 8 x 8 grid board, where board[r][c] represents the cell (r, c) on a game board. On the board, free cells are represented by '.', white cells are represented by 'W', and black cells are represented by 'B'.
+ * Each move in this game consists of choosing a free cell and changing it to the color you are playing as (either white or black). However, a move is only legal if, after changing it, the cell becomes the endpoint of a good line (horizontal, vertical, or diagonal).
+ * A good line is a line of three or more cells (including the endpoints) where the endpoints of the line are one color, and the remaining cells in the middle are the opposite color (no cells in the line are free). You can find examples for good lines in the figure below:
+ * <img alt="" src="https://assets.leetcode.com/uploads/2021/07/22/goodlines5.png" style="width: 500px; height: 312px;" />
+ * Given two integers rMove and cMove and a character color representing the color you are playing as (white or black), return true if changing cell (rMove, cMove) to color color is a legal move, or false if it is not legal.
+ *  
+ * Example 1:
+ * <img alt="" src="https://assets.leetcode.com/uploads/2021/07/10/grid11.png" style="width: 350px; height: 350px;" />
+ * Input: board = [[".",".",".","B",".",".",".","."],[".",".",".","W",".",".",".","."],[".",".",".","W",".",".",".","."],[".",".",".","W",".",".",".","."],["W","B","B",".","W","W","W","B"],[".",".",".","B",".",".",".","."],[".",".",".","B",".",".",".","."],[".",".",".","W",".",".",".","."]], rMove = 4, cMove = 3, color = "B"
+ * Output: true
+ * Explanation: '.', 'W', and 'B' are represented by the colors blue, white, and black respectively, and cell (rMove, cMove) is marked with an 'X'.
+ * The two good lines with the chosen cell as an endpoint are annotated above with the red rectangles.
+ *
+ * Example 2:
+ * <img alt="" src="https://assets.leetcode.com/uploads/2021/07/10/grid2.png" style="width: 350px; height: 351px;" />
+ * Input: board = [[".",".",".",".",".",".",".","."],[".","B",".",".","W",".",".","."],[".",".","W",".",".",".",".","."],[".",".",".","W","B",".",".","."],[".",".",".",".",".",".",".","."],[".",".",".",".","B","W",".","."],[".",".",".",".",".",".","W","."],[".",".",".",".",".",".",".","B"]], rMove = 4, cMove = 4, color = "W"
+ * Output: false
+ * Explanation: While there are good lines with the chosen cell as a middle cell, there are no good lines with the chosen cell as an endpoint.
+ *
+ *  
+ * Constraints:
+ *
+ * 	board.length == board[r].length == 8
+ * 	0 <= rMove, cMove < 8
+ * 	board[rMove][cMove] == '.'
+ * 	color is either 'B' or 'W'.
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/check-if-move-is-legal/
+// discuss: https://leetcode.com/problems/check-if-move-is-legal/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    // Credit: https://leetcode.com/problems/check-if-move-is-legal/solutions/3241963/just-a-runnable-solution/
+    pub fn check_move(board: Vec<Vec<char>>, r_move: i32, c_move: i32, color: char) -> bool {
+        let x_arr = [0, 0, 1, -1, 1, -1, -1, 1];
+        let y_arr = [1, -1, 0, 0, 1, -1, 1, -1];
+        for i in 0..8 {
+            let mut x = r_move + x_arr[i];
+            let mut y = c_move + y_arr[i];
+            let mut count = 0;
+            while x < board.len() as i32 && x >= 0 && y < board[i].len() as i32 && y >= 0 {
+                if board[x as usize][y as usize] == '.' {
+                    break;
+                } else if board[x as usize][y as usize] != color {
+                    count += 1;
+                } else if board[x as usize][y as usize] == color && count < 1 {
+                    break;
+                } else if board[x as usize][y as usize] == color && count >= 1 {
+                    return true;
+                }
+                x += x_arr[i];
+                y += y_arr[i];
+            }
+        }
+        false
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1958_example_1() {
+        let board = vec![
+            vec!['.', '.', '.', 'B', '.', '.', '.', '.'],
+            vec!['.', '.', '.', 'W', '.', '.', '.', '.'],
+            vec!['.', '.', '.', 'W', '.', '.', '.', '.'],
+            vec!['.', '.', '.', 'W', '.', '.', '.', '.'],
+            vec!['W', 'B', 'B', '.', 'W', 'W', 'W', 'B'],
+            vec!['.', '.', '.', 'B', '.', '.', '.', '.'],
+            vec!['.', '.', '.', 'B', '.', '.', '.', '.'],
+            vec!['.', '.', '.', 'W', '.', '.', '.', '.'],
+        ];
+        let r_move = 4;
+        let c_move = 3;
+        let color = 'B';
+
+        let result = true;
+
+        assert_eq!(Solution::check_move(board, r_move, c_move, color), result);
+    }
+
+    #[test]
+    fn test_1958_example_2() {
+        let board = vec![
+            vec!['.', '.', '.', '.', '.', '.', '.', '.'],
+            vec!['.', 'B', '.', '.', 'W', '.', '.', '.'],
+            vec!['.', '.', 'W', '.', '.', '.', '.', '.'],
+            vec!['.', '.', '.', 'W', 'B', '.', '.', '.'],
+            vec!['.', '.', '.', '.', '.', '.', '.', '.'],
+            vec!['.', '.', '.', '.', 'B', 'W', '.', '.'],
+            vec!['.', '.', '.', '.', '.', '.', 'W', '.'],
+            vec!['.', '.', '.', '.', '.', '.', '.', 'B'],
+        ];
+        let r_move = 4;
+        let c_move = 4;
+        let color = 'W';
+
+        let result = false;
+
+        assert_eq!(Solution::check_move(board, r_move, c_move, color), result);
+    }
+}