Add solution #1568

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,373 LeetCode solutions in JavaScript
+# 1,374 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
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 1563|[Stone Game V](./solutions/1563-stone-game-v.js)|Hard|
 1566|[Detect Pattern of Length M Repeated K or More Times](./solutions/1566-detect-pattern-of-length-m-repeated-k-or-more-times.js)|Easy|
 1567|[Maximum Length of Subarray With Positive Product](./solutions/1567-maximum-length-of-subarray-with-positive-product.js)|Medium|
+1568|[Minimum Number of Days to Disconnect Island](./solutions/1568-minimum-number-of-days-to-disconnect-island.js)|Hard|
 1576|[Replace All ?'s to Avoid Consecutive Repeating Characters](./solutions/1576-replace-all-s-to-avoid-consecutive-repeating-characters.js)|Medium|
 1598|[Crawler Log Folder](./solutions/1598-crawler-log-folder.js)|Easy|
 1657|[Determine if Two Strings Are Close](./solutions/1657-determine-if-two-strings-are-close.js)|Medium|

solutions/1568-minimum-number-of-days-to-disconnect-island.js

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+/**
+ * 1568. Minimum Number of Days to Disconnect Island
+ * https://leetcode.com/problems/minimum-number-of-days-to-disconnect-island/
+ * Difficulty: Hard
+ *
+ * You are given an m x n binary grid grid where 1 represents land and 0 represents water. An
+ * island is a maximal 4-directionally (horizontal or vertical) connected group of 1's.
+ *
+ * The grid is said to be connected if we have exactly one island, otherwise is said disconnected.
+ *
+ * In one day, we are allowed to change any single land cell (1) into a water cell (0).
+ *
+ * Return the minimum number of days to disconnect the grid.
+ */
+
+/**
+ * @param {number[][]} grid
+ * @return {number}
+ */
+var minDays = function(grid) {
+  const rows = grid.length;
+  const cols = grid[0].length;
+
+  if (countIslands() !== 1) return 0;
+
+  for (let r = 0; r < rows; r++) {
+    for (let c = 0; c < cols; c++) {
+      if (grid[r][c] === 1) {
+        grid[r][c] = 0;
+        if (countIslands() !== 1) return 1;
+        grid[r][c] = 1;
+      }
+    }
+  }
+
+  return 2;
+
+  function countIslands() {
+    const visited = Array(rows).fill().map(() => Array(cols).fill(false));
+    let islands = 0;
+
+    function dfs(row, col) {
+      if (row < 0 || row >= rows || col < 0 || col >= cols
+          || visited[row][col] || grid[row][col] === 0) {
+        return;
+      }
+      visited[row][col] = true;
+      dfs(row + 1, col);
+      dfs(row - 1, col);
+      dfs(row, col + 1);
+      dfs(row, col - 1);
+    }
+
+    for (let r = 0; r < rows; r++) {
+      for (let c = 0; c < cols; c++) {
+        if (grid[r][c] === 1 && !visited[r][c]) {
+          islands++;
+          dfs(r, c);
+        }
+      }
+    }
+    return islands;
+  }
+};