Create 980-unique-paths-iii.js

Author: everthis

980-unique-paths-iii.js

@@ -0,0 +1,42 @@
+/**
+ * @param {number[][]} grid
+ * @return {number}
+ */
+const uniquePathsIII = function(grid) {
+  const obj = {
+    eNum: 1,
+    res: 0,
+    rows: grid.length,
+    dirs: [[-1, 0], [1, 0], [0, -1], [0, 1]],
+    sr: 0,
+    sc: 0,
+    er: 0,
+    ec: 0
+  }
+  if (obj.rows === 0) return 0
+  obj.cols = grid[0].length
+  for (let i = 0; i < obj.rows; i++) {
+    for (let j = 0; j < obj.cols; j++) {
+      if (grid[i][j] === 0) obj.eNum++
+      else if (grid[i][j] === 1) (obj.sr = i), (obj.sc = j)
+      else if (grid[i][j] === 2) (obj.er = i), (obj.ec = j)
+    }
+  }
+  bt(grid, obj.sr, obj.sc, obj)
+  return obj.res
+}
+
+function bt(grid, x, y, obj) {
+  if (x < 0 || x >= obj.rows || y < 0 || y >= obj.cols || grid[x][y] < 0) return
+  if (x === obj.er && y === obj.ec) {
+    if (obj.eNum === 0) obj.res++
+    return
+  }
+  grid[x][y] = -2
+  obj.eNum--
+  for (let dir of obj.dirs) {
+    bt(grid, x + dir[0], y + dir[1], obj)
+  }
+  obj.eNum++
+  grid[x][y] = 0
+}