Update 1559-detect-cycles-in-2d-grid.js

Author: everthis

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

@@ -1,3 +1,51 @@
+/**
+ * @param {character[][]} grid
+ * @return {boolean}
+ */
+const containsCycle = function (grid) {
+  const dirs = [
+    [1, 0],
+    [-1, 0],
+    [0, 1],
+    [0, -1],
+  ]
+  const rows = grid.length
+  const cols = (grid[0] || []).length
+  const vis = Array.from({ length: rows }, () => Array(cols).fill(false))
+  let res = false
+  const dfs = (i, j, prevR, prevC, char) => {
+    vis[i][j] = true
+    for (let d of dirs) {
+      const r = i + d[0]
+      const c = j + d[1]
+      if (r >= 0 && r < rows && c >= 0 && c < cols) {
+        if (!(r == prevR && c === prevC)) {
+          if (grid[r][c] === char) {
+            if (!vis[r][c]) {
+              if (dfs(r, c, i, j, char)) return true
+            } else {
+              if (prevR !== -1 && prevC !== -1) return true
+            }
+          }
+        }
+      }
+    }
+    return false
+  }
+
+  for (let i = 0; i < rows; i++) {
+    for (let j = 0; j < cols; j++) {
+      if (!vis[i][j]) {
+        res |= dfs(i, j, -1, -1, grid[i][j])
+      }
+      if (res) return true
+    }
+  }
+  return res
+}
+
+// another
+
 /**
  * @param {character[][]} grid
  * @return {boolean}