Create stone-game-ii.cpp

Author: kamyu104

C++/stone-game-ii.cpp

@@ -0,0 +1,30 @@
+// Time:  O(n*(logn)^2)
+// Space: O(nlogn)
+
+class Solution {
+public:
+    int stoneGameII(vector<int>& piles) {
+        for (int i = piles.size() - 2; i >= 0; --i) {
+            piles[i] += piles[i + 1];
+        }
+        unordered_map<int, unordered_map<int, int>> lookup;
+        return dp(piles, &lookup, 0, 1);
+    }
+
+private:
+    int dp(const vector<int>& piles,
+           unordered_map<int, unordered_map<int, int>> *lookup,
+           int i, int m) {
+        if (i + 2 * m >= piles.size()) {
+            return piles[i];
+        }
+        if (!lookup->count(i) || !(*lookup)[i].count(m)) {
+            int min_dp = numeric_limits<int>::max();
+            for (int x = 1; x <= 2 * m; ++x) {
+                min_dp = min(min_dp, dp(piles, lookup, i + x, max(m, x)));
+            }
+            (*lookup)[i][m] = piles[i] - min_dp;
+        }
+        return (*lookup)[i][m];
+    }
+};