208th Commit

README.md

@@ -213,10 +213,12 @@ Ace Coding Interview with 75 Qs
 [1466]: ./src/page-14/1466.%20Reorder%20Routes%20to%20Make%20All%20Paths%20Lead%20to%20the%20City%20Zero/minReorder.ts
 [399]: ./src/page-4/399.%20Evaluate%20Division/calcEquation.ts
 
-| Graphs - BFS                             |          |        |
-| ---------------------------------------- | -------- | ------ |
-| 1926. Nearest Exit from Entrance in Maze | Solution | Medium |
-| 994. Rotting Oranges                     | Solution | Medium |
+| Graphs - BFS                             |                  |        |
+| ---------------------------------------- | ---------------- | ------ |
+| 1926. Nearest Exit from Entrance in Maze | [Solution][1926] | Medium |
+| 994. Rotting Oranges                     | Solution         | Medium |
+
+[1926]: ./src/page-18/1926.%20Nearest%20Exit%20from%20Entrance%20in%20Maze/nearestExit.ts
 
 | Heap / Priority Queue                 |          |        |
 | ------------------------------------- | -------- | ------ |

src/page-18/1926. Nearest Exit from Entrance in Maze/nearestExit.test.ts

@@ -0,0 +1,29 @@
+import { nearestExit } from './nearestExit';
+
+describe('1926. Nearest Exit from Entrance in Maze', () => {
+  test('nearestExit', () => {
+    expect(
+      nearestExit(
+        [
+          ['+', '+', '.', '+'],
+          ['.', '.', '.', '+'],
+          ['+', '+', '+', '.'],
+        ],
+        [1, 2],
+      ),
+    ).toBe(1);
+
+    expect(
+      nearestExit(
+        [
+          ['+', '+', '+'],
+          ['.', '.', '.'],
+          ['+', '+', '+'],
+        ],
+        [1, 0],
+      ),
+    ).toBe(2);
+
+    expect(nearestExit([['.', '+']], [0, 0])).toBe(-1);
+  });
+});

src/page-18/1926. Nearest Exit from Entrance in Maze/nearestExit.ts

@@ -0,0 +1,63 @@
+type NearestExit = (maze: string[][], entrance: number[]) => number;
+
+/**
+ * Accepted
+ */
+export const nearestExit: NearestExit = (maze, entrance) => {
+  const rows = maze.length;
+  const cols = maze[0].length;
+
+  // Directions for moving up, down, left, and right.
+  const directions = [
+    [-1, 0], // Up
+    [1, 0], // Down
+    [0, -1], // Left
+    [0, 1], // Right
+  ];
+
+  const queue: [number, number, number][] = []; // [row, col, steps]
+  const [startRow, startCol] = entrance;
+
+  // Start BFS from the entrance
+  queue.push([startRow, startCol, 0]);
+  maze[startRow][startCol] = '+'; // Mark the entrance as visited by converting it to a wall.
+
+  while (queue.length > 0) {
+    const current = queue.shift();
+    if (current === undefined) continue; // Safely handle empty queue
+
+    const [row, col, steps] = current;
+
+    // Check all four possible directions.
+    for (const [dRow, dCol] of directions) {
+      const newRow = row + dRow;
+      const newCol = col + dCol;
+
+      // If the new position is out of bounds or is a wall, skip it.
+      if (
+        newRow < 0 ||
+        newRow >= rows ||
+        newCol < 0 ||
+        newCol >= cols ||
+        maze[newRow][newCol] === '+'
+      ) {
+        continue;
+      }
+
+      // Check if the new position is an exit (on the border) and not the entrance.
+      if (
+        (newRow === 0 || newRow === rows - 1 || newCol === 0 || newCol === cols - 1) &&
+        (newRow !== startRow || newCol !== startCol)
+      ) {
+        return steps + 1; // We found the nearest exit.
+      }
+
+      // Mark the cell as visited and add it to the queue.
+      maze[newRow][newCol] = '+';
+      queue.push([newRow, newCol, steps + 1]);
+    }
+  }
+
+  // No exit found.
+  return -1;
+};