feat: Upload number-of-islands(typescript)

Author: mike2ox

number-of-islands/mike2ox.ts

@@ -0,0 +1,58 @@
+/**
+ * https://leetcode.com/problems/number-of-islands/
+ * 풀이방법: BFS를 사용하여 섬의 개수를 구함
+ *
+ * 시간복잡도: O(n * m) (n: 그리드의 행, m: 그리드의 열)
+ * 공간복잡도: O(n * m) (그리드의 모든 요소를 방문)
+ */
+
+function numIslands(grid: string[][]): number {
+  if (!grid.length) return 0; // 그리드가 비어있는 경우
+
+  const rows = grid.length;
+  const cols = grid[0].length;
+  let islands = 0;
+
+  const bfs = (startRow: number, startCol: number) => {
+    const q: number[][] = [[startRow, startCol]];
+    grid[startRow][startCol] = "0";
+
+    const directions = [
+      [1, 0],
+      [-1, 0],
+      [0, 1],
+      [0, -1],
+    ]; // 상하좌우
+
+    while (q.length) {
+      const [r, c] = q.shift()!;
+
+      for (const [dx, dy] of directions) {
+        const newR = r + dx;
+        const newC = c + dy;
+
+        if (
+          newR >= 0 &&
+          newR < rows &&
+          newC >= 0 &&
+          newC < cols &&
+          grid[newR][newC] === "1"
+        ) {
+          q.push([newR, newC]);
+          grid[newR][newC] = "0";
+        }
+      }
+    }
+  };
+
+  for (let r = 0; r < rows; r++) {
+    for (let c = 0; c < cols; c++) {
+      if (grid[r][c] === "1") {
+        islands++;
+        bfs(r, c);
+      }
+    }
+  }
+
+  return islands;
+}