feat: 黄金矿工

Author: sl1673495

递归与回溯/黄金矿工-1219.js

@@ -0,0 +1,69 @@
+/**
+ * @param {number[][]} grid
+ * @return {number}
+ */
+let getMaximumGold = function (grid) {
+  let maxY = grid.length
+  if (maxY === 0) {
+    return 0
+  }
+  let maxX = grid[0].length
+
+  let visited = []
+  for (let y = 0; y < maxY; y++) {
+    visited[y] = []
+  }
+
+  let dirs = [
+    [1, 0],
+    [-1, 0],
+    [0, -1],
+    [0, 1],
+  ]
+
+  // 验证是否能走入这个格子
+  // 1. 范围不能越界
+  // 2. 本轮递归中未访问过
+  // 3. 格子的值不能为 0
+  let isValid = (y, x) => {
+    return (
+      y >= 0 &&
+      y < maxY &&
+      x >= 0 &&
+      x < maxX &&
+      grid[y][x] !== 0 &&
+      !visited[y][x]
+    )
+  }
+
+  let maxGold = 0
+  let helper = (y, x, prevGold) => {
+    let val = grid[y][x]
+    let curGold = prevGold + val
+    if (curGold === 0) {
+      return
+    }
+
+    for (let dir of dirs) {
+      let [diffY, diffX] = dir
+      let nextY = y + diffY
+      let nextX = x + diffX
+      if (isValid(nextY, nextX)) {
+        visited[y][x] = true
+        helper(nextY, nextX, curGold)
+        visited[y][x] = false
+      } else {
+        // 走到尽头或者不符合条件的了
+        maxGold = Math.max(maxGold, curGold)
+      }
+    }
+  }
+
+  for (let y = 0; y < maxY; y++) {
+    for (let x = 0; x < maxX; x++) {
+      helper(y, x, 0)
+    }
+  }
+
+  return maxGold
+}