From 6d18cb0d950c964ccc9a1c4d8dcc1161301fbaec Mon Sep 17 00:00:00 2001
From: bangdori <qudwns8865@naver.com>
Date: Thu, 12 Jun 2025 11:33:36 +0900
Subject: [PATCH] =?UTF-8?q?[=EA=B0=95=EB=B3=91=EC=A4=80]=20Number=20of=20I?=
 =?UTF-8?q?slands?=
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---
 bangdori/200.js | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 bangdori/200.js

diff --git a/bangdori/200.js b/bangdori/200.js
new file mode 100644
index 0000000..6560736
--- /dev/null
+++ b/bangdori/200.js
@@ -0,0 +1,48 @@
+const LAND = "1";
+const WATER = "0";
+
+const dirs = [
+  [-1, 0],
+  [1, 0],
+  [0, 1],
+  [0, -1],
+];
+
+/**
+ * @param {character[][]} grid
+ * @return {number}
+ */
+var numIslands = function (grid) {
+  const ySize = grid.length;
+  const xSize = grid[0].length;
+
+  const visited = Array.from({ length: ySize }, () => Array(xSize).fill(false));
+  let answer = 0;
+
+  const dfs = (y, x) => {
+    if (visited[y][x]) return;
+
+    visited[y][x] = true;
+
+    for (let [dy, dx] of dirs) {
+      const ny = y + dy;
+      const nx = x + dx;
+
+      if (ny < 0 || ny >= ySize || nx < 0 || nx >= xSize) continue;
+      if (visited[ny][nx] || grid[ny][nx] === WATER) continue;
+
+      dfs(ny, nx);
+    }
+  };
+
+  for (let y = 0; y < ySize; y++) {
+    for (let x = 0; x < xSize; x++) {
+      if (visited[y][x] || grid[y][x] === WATER) continue;
+
+      answer++;
+      dfs(y, x);
+    }
+  }
+
+  return answer;
+};