add Number of Islands solution

Author: HoonDongKang

number-of-islands/HoonDongKang.ts

@@ -0,0 +1,80 @@
+/**
+ * [Problem]: [200] Number of Islands
+ * (https://leetcode.com/problems/number-of-islands/description/)
+ */
+function numIslands(grid: string[][]): number {
+    //시간복잡도 O(n)
+    //공간복잡도 O(n)
+    function dfsFunc(grid: string[][]): number {
+        let rows = grid.length;
+        let cols = grid[0].length;
+        let count = 0;
+
+        for (let i = 0; i < rows; i++) {
+            for (let j = 0; j < cols; j++) {
+                if (grid[i][j] === "1") {
+                    count++;
+                    traveling(i, j);
+                }
+            }
+        }
+
+        function traveling(i: number, j: number) {
+            grid[i][j] = "#";
+
+            [
+                [i - 1, j],
+                [i + 1, j],
+                [i, j - 1],
+                [i, j + 1],
+            ].forEach(([r, c]) => {
+                if (0 <= r && r < rows && 0 <= c && c < cols) {
+                    if (grid[r][c] === "1") traveling(r, c);
+                }
+            });
+        }
+
+        return count;
+    }
+
+    //시간복잡도 O(n)
+    //공간복잡도 O(n)
+    function stackFunc(grid: string[][]): number {
+        let rows = grid.length;
+        let cols = grid[0].length;
+        let count = 0;
+
+        for (let i = 0; i < rows; i++) {
+            for (let j = 0; j < cols; j++) {
+                if (grid[i][j] === "1") {
+                    count++;
+                    traveling(i, j);
+                }
+            }
+        }
+
+        function traveling(i: number, j: number) {
+            let stack = [[i, j]];
+
+            while (stack.length) {
+                let [r, c] = stack.pop()!;
+                grid[r][c] = "#";
+
+                [
+                    [r - 1, c],
+                    [r + 1, c],
+                    [r, c - 1],
+                    [r, c + 1],
+                ].forEach(([r, c]) => {
+                    if (0 <= r && r < rows && 0 <= c && c < cols) {
+                        if (grid[r][c] === "1") stack.push([r, c]);
+                    }
+                });
+            }
+        }
+
+        return count;
+    }
+
+    return stackFunc(grid);
+}