Create: 200-Number-of-Islands.ts

Author: andra961

Diff for: typescript/200-Number-of-Islands.ts

@@ -0,0 +1,54 @@
+//BFS way to solve this
+const bfs = (grid, r, c) => {
+    const [ROWS, COLS] = [grid.length, grid[0].length];
+
+    const directions = [
+        [-1, 0],
+        [1, 0],
+        [0, -1],
+        [0, 1],
+    ];
+
+    let queue = [[r, c]];
+
+    //marks as visited
+    grid[r][c] = '0';
+
+    while (queue.length > 0) {
+        //dequeues the first element(current)
+        let [cr, cc] = queue.shift();
+
+        directions.forEach(([dr, dc]) => {
+            let [nr, nc] = [cr + dr, cc + dc];
+            if (
+                !(
+                    nr < 0 ||
+                    nc < 0 ||
+                    nr >= ROWS ||
+                    nc >= COLS ||
+                    grid[nr][nc] === '0'
+                )
+            ) {
+                queue.push([nr, nc]);
+                grid[nr][nc] = '0';
+            }
+        });
+    }
+};
+
+function numIslands(grid: string[][]): number {
+    const [ROWS, COLS] = [grid.length, grid[0].length];
+
+    let islands = 0;
+
+    for (let i = 0; i < ROWS; i++) {
+        for (let j = 0; j < COLS; j++) {
+            if (grid[i][j] === '1') {
+                bfs(grid, i, j);
+                islands++;
+            }
+        }
+    }
+
+    return islands;
+}