Create 1463-cherry-pickup-ii.js

javascript/1463-cherry-pickup-ii.js

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+/**
+ * 2D-DP | Memoization
+ * Time O(n^3) | Space O(n^3);
+ * https://leetcode.com/problems/cherry-pickup-ii/
+ * @param {number[][]} grid
+ * @return {number}
+ */
+var cherryPickup = function(grid) {
+
+    const ROW = grid.length;
+    const COL = grid[0].length;
+    const cache = new Map();
+
+    const columnOutOfBound = (c) => {
+        if (c < 0) return true;
+        if (c === COL) return true;
+        return false;
+    }
+
+    const dfs = (r1, c1, c2) => {
+
+        const hash = `${r1}-${c1}-${c2}`;
+        if (cache.has(hash)) return cache.get(hash);
+        if (columnOutOfBound(c1) || columnOutOfBound(c2)) return 0;
+        if (r1 === ROW) return 0;
+
+        const currTwoRobotSum = grid[r1][c1] + (c1 !== c2 && grid[r1][c2] || 0)
+
+        let max = 0;
+        for (let i = c1-1; i < c1+2; i++) {
+            for (let j = c2-1; j < c2+2; j++) {
+               max = Math.max(max, currTwoRobotSum + dfs(r1+1, i, j));
+            }
+        }
+
+        cache.set(hash, max);
+        return max;
+    }
+
+    return dfs(0,0, COL-1);
+};