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Diffstat (limited to 'stone_game.c')
-rw-r--r-- | stone_game.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/stone_game.c b/stone_game.c new file mode 100644 index 0000000..96072d1 --- /dev/null +++ b/stone_game.c @@ -0,0 +1,45 @@ +// 877. Stone Game +#include "leetcode.h" + +/* + * alice and bob play a game with piles of stones. there are an even 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. + * the total number of stones across all piles isodd, so there are no ties. + * alice and bob take turns, with alice starting first. each turn a player takes + * the entire pile of stones either from the beginning or from the end of the + * row. this continues until there are no more piles left, at which point the + * person with the most stones wins. assuming alice and bob play optimally, + * return 'true' if alice wins the game, or 'false' if bob wins. + */ + +bool stoneGame(int *piles, int piles_size) { + int **dp = (int **)malloc(sizeof(int *) * piles_size); + int **sum = (int **)malloc(sizeof(int *) * piles_size); + for (int i = 0; i < piles_size; i++) { + dp[i] = (int *)malloc(sizeof(int) * piles_size); + sum[i] = (int *)malloc(sizeof(int) * piles_size); + for (int j = 0; j < piles_size; j++) + if (i == j) { + dp[i][j] = piles[i]; + sum[i][j] = piles[i]; + } + } + for (int l = 2; l <= piles_size; ++l) + for (int i = 0; i <= piles_size; ++i) { + int j = i + l - 1; + sum[i][j] = sum[i][j - 1] + piles[j]; + dp[i][j] = sum[i][j] - fmin(dp[i][j - 1], dp[i + 1][j]); + } + bool ans = (dp[0][piles_size - 1] * 2 > sum[0][piles_size - 1]); + for (int i = 0; i < piles_size; i++) + free(dp[i]), free(sum[i]); + free(dp), free(sum); + return ans; +} + +int main() { + int p1[] = {5, 3, 4, 5}, p2[] = {3, 7, 2, 3}; + printf("%d\n", stoneGame(p1, ARRAY_SIZE(p1))); // expect: 1 + printf("%d\n", stoneGame(p2, ARRAY_SIZE(p2))); // expect: 1 +} |