Create 200-number-of-islands.js

Author: everthis

200-number-of-islands.js

@@ -0,0 +1,33 @@
+/**
+ * @param {character[][]} grid
+ * @return {number}
+ */
+const numIslands = function(grid) {
+    if (grid.length === 0) return 0;
+    const totalRow = grid.length;
+    const totalCol = grid[0].length;
+    let res = 0;
+    
+    for (let i = 0; i < totalRow; i += 1) {
+        for (let j = 0; j < totalCol; j += 1) {
+            if (grid[i][j] === '1') {
+                res += 1;
+                dfs(grid, i, j, totalRow, totalCol);
+            }
+        }
+    }
+    
+    return res;
+};
+
+const dfs = (grid, row, col, totalRow, totalCol) => {
+    if (row < 0 || col < 0 || row === totalRow || col === totalCol || grid[row][col] === '0') {
+       return;
+    }
+    
+    grid[row][col] = '0';
+    dfs(grid, row - 1, col, totalRow, totalCol);
+    dfs(grid, row + 1, col, totalRow, totalCol);
+    dfs(grid, row, col - 1, totalRow, totalCol);
+    dfs(grid, row, col + 1, totalRow, totalCol);
+}