Update 1091-shortest-path-in-binary-matrix.js

Author: everthis

1091-shortest-path-in-binary-matrix.js

@@ -32,3 +32,49 @@ const shortestPathBinaryMatrix = function(grid) {
   }
   return -1
 };
+
+// another
+
+/**
+ * @param {number[][]} grid
+ * @return {number}
+ */
+const shortestPathBinaryMatrix = function(grid) {
+  if(grid == null || grid.length === 0 || grid[0][0] === 1) return -1 
+  let res = 1
+  const n = grid.length
+  const dirs = [
+    [1, 0],
+    [-1, 0],
+    [0, 1],
+    [0, -1],
+    [-1, -1],
+    [-1, 1],
+    [1, 1],
+    [1, -1],
+  ]
+  let q = [[0, 0]]
+  while(q.length) {
+    let ref = q
+    q = []
+    for(let [x, y] of ref) {
+      if(x === n - 1 && y === n - 1) return res
+      grid[x][y] = 1
+      for(let [dx, dy] of dirs) {
+        const nx = x + dx, ny = y + dy
+        if(helper(grid, nx, ny)) {
+          q.push([nx, ny])
+          grid[nx][ny] = 1 // very important
+        }
+      }
+    }
+    res++
+  }
+  return -1
+};
+
+function helper(grid, i, j) {
+  const n = grid.length
+  if(i < 0 || i >= n || j < 0 || j >= n || grid[i][j] !== 0) return false
+  return true
+}