题目：

题解：

int maxProfit(int k, int* prices, int pricesSize) {
    int n = pricesSize;
    if (n == 0) {
        return 0;
    }

    k = fmin(k, n / 2);
    int buy[k + 1], sell[k + 1];
    memset(buy, 0, sizeof(buy));
    memset(sell, 0, sizeof(sell));

    buy[0] = -prices[0];
    sell[0] = 0;
    for (int i = 1; i <= k; ++i) {
        buy[i] = sell[i] = INT_MIN / 2;
    }

    for (int i = 1; i < n; ++i) {
        buy[0] = fmax(buy[0], sell[0] - prices[i]);
        for (int j = 1; j <= k; ++j) {
            buy[j] = fmax(buy[j], sell[j] - prices[i]);
            sell[j] = fmax(sell[j], buy[j - 1] + prices[i]);
        }
    }
    int ret = 0;
    for (int i = 0; i <= k; i++) {
        ret = fmax(ret, sell[i]);
    }

    return ret;
}