number of islands solved

Author: hsskey

number-of-islands/hsskey.js

@@ -0,0 +1,56 @@
+/**
+ * @param {character[][]} grid
+ * @return {number}
+ */
+var numIslands = function(grid) {
+    if (!grid.length) return 0;
+
+    const rows = grid.length;
+    const cols = grid[0].length;
+    const visit = new Set();
+    let islands = 0;
+
+    const bfs = (r, c) => {
+        const queue = [];
+        queue.push([r, c]);
+        visit.add(`${r},${c}`);
+
+        while (queue.length) {
+            const [row, col] = queue.shift();
+            const directions = [
+                [1, 0],
+                [-1, 0],
+                [0, 1],
+                [0, -1],
+            ];
+
+            for (const [dr, dc] of directions) {
+                const newRow = row + dr;
+                const newCol = col + dc;
+
+                if (
+                    newRow >= 0 &&
+                    newRow < rows &&
+                    newCol >= 0 &&
+                    newCol < cols &&
+                    grid[newRow][newCol] === '1' &&
+                    !visit.has(`${newRow},${newCol}`)
+                ) {
+                    queue.push([newRow, newCol]);
+                    visit.add(`${newRow},${newCol}`);
+                }
+            }
+        }
+    };
+
+    for (let r = 0; r < rows; r++) {
+        for (let c = 0; c < cols; c++) {
+            if (grid[r][c] === '1' && !visit.has(`${r},${c}`)) {
+                bfs(r, c);
+                islands += 1;
+            }
+        }
+    }
+
+    return islands;
+};