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

Author: everthis

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

@@ -0,0 +1,53 @@
+/**
+ * @param {character[][]} grid
+ * @return {boolean}
+ */
+const containsCycle = function (grid) {
+  const wholePath = (r, c, letter, component, last = [-1, -1]) => {
+    const dirs = [
+      [0, -1],
+      [0, 1],
+      [-1, 0],
+      [1, 0],
+    ]
+    const tmp = grid[r][c]
+    grid[r][c] = component
+    const nextSteps = dirs
+      .map((x) => [x[0] + r, x[1] + c])
+      .filter(
+        (x) =>
+          x[0] >= 0 && x[0] < grid.length && x[1] >= 0 && x[1] < grid[0].length
+      )
+    for (let step of nextSteps) {
+      if (step[0] === last[0] && last[1] === step[1]) {
+        continue
+      }
+      if (grid[step[0]][step[1]] === component) {
+        return true
+      }
+      if (grid[step[0]][step[1]] === letter) {
+        let outcome = wholePath(step[0], step[1], letter, component, [r, c])
+        if (outcome) {
+          return true
+        }
+      }
+    }
+    return false
+  }
+
+  let component = 1
+  for (let r = 0; r < grid.length; r++) {
+    for (let c = 0; c < grid[0].length; c++) {
+      const letter = grid[r][c]
+      if (typeof letter === 'string') {
+        grid[r][c] = component
+        const outcome = wholePath(r, c, letter, component)
+        if (outcome) {
+          return true
+        }
+        component++
+      }
+    }
+  }
+  return false
+}