Add solution #1559

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,367 LeetCode solutions in JavaScript
+# 1,368 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1190,6 +1190,7 @@
 1556|[Thousand Separator](./solutions/1556-thousand-separator.js)|Easy|
 1557|[Minimum Number of Vertices to Reach All Nodes](./solutions/1557-minimum-number-of-vertices-to-reach-all-nodes.js)|Medium|
 1558|[Minimum Numbers of Function Calls to Make Target Array](./solutions/1558-minimum-numbers-of-function-calls-to-make-target-array.js)|Medium|
+1559|[Detect Cycles in 2D Grid](./solutions/1559-detect-cycles-in-2d-grid.js)|Medium|
 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|
 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|

solutions/1559-detect-cycles-in-2d-grid.js

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+/**
+ * 1559. Detect Cycles in 2D Grid
+ * https://leetcode.com/problems/detect-cycles-in-2d-grid/
+ * Difficulty: Medium
+ *
+ * Given a 2D array of characters grid of size m x n, you need to find if there exists any cycle
+ * consisting of the same value in grid.
+ *
+ * A cycle is a path of length 4 or more in the grid that starts and ends at the same cell. From
+ * a given cell, you can move to one of the cells adjacent to it - in one of the four directions
+ * (up, down, left, or right), if it has the same value of the current cell.
+ *
+ * Also, you cannot move to the cell that you visited in your last move. For example, the cycle
+ * (1, 1) -> (1, 2) -> (1, 1) is invalid because from (1, 2) we visited (1, 1) which was the last
+ * visited cell.
+ *
+ * Return true if any cycle of the same value exists in grid, otherwise, return false.
+ */
+
+/**
+ * @param {character[][]} grid
+ * @return {boolean}
+ */
+var containsCycle = function(grid) {
+  const rows = grid.length;
+  const cols = grid[0].length;
+  const visited = new Set();
+
+  for (let row = 0; row < rows; row++) {
+    for (let col = 0; col < cols; col++) {
+      if (!visited.has(`${row},${col}`)) {
+        if (explorePath(row, col, -1, -1, grid[row][col])) return true;
+      }
+    }
+  }
+
+  return false;
+
+  function explorePath(row, col, prevRow, prevCol, char) {
+    const key = `${row},${col}`;
+    if (visited.has(key)) return true;
+    visited.add(key);
+
+    const directions = [[-1, 0], [1, 0], [0, -1], [0, 1]];
+    for (const [dx, dy] of directions) {
+      const newRow = row + dx;
+      const newCol = col + dy;
+
+      if (newRow === prevRow && newCol === prevCol) continue;
+      if (newRow < 0 || newRow >= rows || newCol < 0 || newCol >= cols) continue;
+      if (grid[newRow][newCol] !== char) continue;
+
+      if (explorePath(newRow, newCol, row, col, char)) return true;
+    }
+
+    return false;
+  }
+};