// 1140. Stone Game II #include "leetcode.h" /* * alice and bob continue their games with piles of stones. there are a number * of piles arranged in a row, and each pile has a positive integer number of * stones 'piles[i]'. the objective of the game is to end with the most stones. * alice and bob take turns, with alice starting first. initiall, 'M = 1'. on * each player's turn, that player can take all the stones on the 'X' remaining * piles, where '1 <= X <= 2M'. then, we set 'M = max(M, X)'. the game continues * until all the stones have been take. assuming alice and bob play optimally, * return maximum stones alice can get. */ int stoneGameII(int *piles, int piles_size) { int n = piles_size; int *sum = (int *)malloc((n + 1) * sizeof(int)); int **dp = (int **)malloc((n + 1) * sizeof(int *)); for (int i = 0; i <= n; i++) dp[i] = (int *)calloc(n + 1, sizeof(int)); sum[n] = 0; for (int i = n - 1; i >= 0; i--) sum[i] = sum[i + 1] + piles[i]; for (int i = 0; i < n; ++i) dp[i][n] = sum[i]; for (int i = n - 1; i >= 0; i--) for (int m = n - 1; m >= 1; m--) for (int x = 1; x <= 2 * m && i + x <= n; ++x) dp[i][m] = fmax(dp[i][m], sum[i] - dp[i + x][(int)fmax(m, x)]); int ans = dp[0][1]; for (int i = 0; i <= n; i++) free(dp[i]); free(dp); free(sum); return ans; } int main() { int p1[] = {2, 7, 9, 4, 4}; int p2[] = {1, 2, 3, 4, 5, 100}; printf("%d\n", stoneGameII(p1, 5)); // expect: 10 printf("%d\n", stoneGameII(p2, 6)); // expect: 104 }