Create Solution.java

Author: Jerring

solution/1140.Stone Game II/Solution.java

@@ -0,0 +1,32 @@
+class Solution {
+    public int stoneGameII(int[] piles) {
+        Map<Integer, Integer> map = new HashMap<>();
+        int total = Arrays.stream(piles).sum();
+        return (total + dfs(0, 1, piles, map)) >> 1;
+    }
+
+    private int dfs(int s, int M, int[] piles, Map<Integer, Integer> map) {
+        if (s >= piles.length) {
+            return 0;
+        }
+        int key = s << 8 | M;
+        if (map.containsKey(key)) {
+            return map.get(key);
+        }
+        if (s + 2 * M >= piles.length) {
+            int res = 0;
+            for (int i = s; i < piles.length; ++i) {
+                res += piles[i];
+            }
+            return res;
+        }
+        int best = Integer.MIN_VALUE;
+        int cur = 0;
+        for (int x = 1; x <= 2 * M && s + x - 1 < piles.length; ++x) {
+            cur += piles[s + x - 1];
+            best = Math.max(best, cur - dfs(s + x, Math.max(x, M), piles, map));
+        }
+        map.put(key, best);
+        return best;
+    }
+}