Leetcode 714 买卖股票的最佳时机含手续费 dp

 

　　C:

#include <stdio.h>
#include <stdlib.h>

int dp(int *prices, int fee, int point, int hasShared, int *cache)
{
    if (point == 0)
    {
        if (hasShared == 0)
            return 0;
        else
            return -prices[0];
    }
    int key = point * 2 + hasShared;
    if (cache[key] != 0)
        return cache[key];
    int re = 0;
    if (hasShared == 0)
    {
        int seal = dp(prices, fee, point - 1, 1, cache) + prices[point] - fee;
        int keep = dp(prices, fee, point - 1, 0, cache);
        re = seal > keep ? seal : keep;
    }
    else
    {
        int add = dp(prices, fee, point - 1, 0, cache) - prices[point];
        int keep = dp(prices, fee, point - 1, 1, cache);
        re = add > keep ? add : keep;
    }
    cache[key] = re;
    return re;
}

int maxProfit(int *prices, int pricesSize, int fee)
{
    int len = pricesSize * 2;
    int *cache = (int *)malloc(sizeof(int) * len);
    for (int i = 0; i < len; i++)
        cache[i] = 0;
    int re = dp(prices, fee, pricesSize - 1, 0, cache);
    free(cache);
    return re;
}

　　JAVA:

 public final int maxProfit(int[] prices, int fee) {
        int len = prices.length;
        int[][] cache = new int[len][2];
        return max(prices, fee, len - 1, 0, cache);
    }

    private final int max(int[] prices, int fee, int point, int hasShares, int[][] cache) {
        if (point == 0 && hasShares == 0) return 0;
        if (point == 0 && hasShares == 1) return -prices[0];
        if (cache[point][hasShares] != 0) return cache[point][hasShares];
        int re;
        if (hasShares == 0) {
            re = Math.max(max(prices, fee, point - 1, 0, cache),
                    max(prices, fee, point - 1, 1, cache) + prices[point] - fee);
        } else {
            re = Math.max(max(prices, fee, point - 1, 1, cache),
                    max(prices, fee, point - 1, 0, cache) - prices[point]);
        }
        cache[point][hasShares] = re;
        return re;
    }

　　JS:

/**
 * @param {number[]} prices
 * @param {number} fee
 * @return {number}
 */
var maxProfit = function (prices, fee) {
    let cache = new Array(prices.length);
    for (let i = 0; i < prices.length; i++) cache[i] = new Array(2).fill(0);
    return dp(prices, fee, prices.length - 1, 0, cache);
};

var dp = function (prices, fee, point, hasShared, cache) {
    if (point == 0) {
        if (hasShared == 0) return 0;
        else return -prices[0];
    }
    if (cache[point][hasShared]) return cache[point][hasShared];
    let re = 0;
    if (hasShared) {
        let get = dp(prices, fee, point - 1, 0, cache) - prices[point];
        let keep = dp(prices, fee, point - 1, 1, cache);
        re = get > keep ? get : keep;
    } else {
        let seal = dp(prices, fee, point - 1, 1, cache) + prices[point] - fee;
        let keep = dp(prices, fee, point - 1, 0, cache);
        re = seal > keep ? seal : keep;
    }
    cache[point][hasShared] = re;
    return re;
}