leetcode(c++)股票问题

#include <iostream>
#include <vector>

using namespace std;

int maxProfit(const vector<int>& prices)
{
    int res = 0;
    int n = prices.size();
    if(n <= 0)
        return 0;
    vector<vector<int>>dp(n,vector<int>(2));
    dp[0][0] = 0;
    dp[0][1] = -prices[0];
    for(int i = 1; i < n; ++i)
    {
        dp[i][1] = max(dp[i-1][1],-prices[i]);
        dp[i][0] = max(dp[i-1][0],dp[i-1][1]+ prices[i]);
    }
    return dp[n-1][0];
}

int maxProfit_greedy(const vector<int>& prices)
{
    if(prices.empty())return 0;
    int n = prices.size();
    int minVal = INT_MAX,profit = 0;
    for(int price:prices)
    {
        minVal = min(minVal,price);
        if(price > minVal)profit = max(profit,price-minVal);
    }
    return profit;
}

int maxProfit_II(const vector<int>& prices)
{
    if(prices.empty())return 0;
    int n = prices.size();
    vector<vector<int>>dp(n,vector<int>(2));
    dp[0][0] = 0;
    dp[0][1] = -prices[0];
    for(int i = 1; i < n; ++i)
    {
        dp[i][1] = max(dp[i-1][1],dp[i-1][0] - prices[i]);
        dp[i][0] = max(dp[i-1][0],dp[i-1][1] + prices[i]);
    }
    return dp[n-1][0];

}

int maxProfit_II_greedy(const vector<int>& prices)
{
    if(prices.empty())return 0;
    int n = prices.size();
    int profit = 0;
    for(int i = 1; i < n; ++i)
    {
        if(prices[i-1] < prices[i])
        {
            profit += (prices[i] - prices[i-1]);
        }
    }
    return profit;
}

int maxprofit(const vector<int>& prices,int fee)
{
    if(prices.empty())return 0;
    int n = prices.size();
    vector<vector<int>>dp(n,vector<int>(2));
    dp[0][0] = 0;
    dp[0][1] = -prices[0];
    for(int i = 1; i < n; ++i)
    {
        dp[i][0] = max(dp[i-1][0],dp[i-1][1]+prices[i]-fee);
        dp[i][1] = max(dp[i-1][0] - prices[i],dp[i-1][1]);
    }
    return dp[n-1][0];

}

int maxProfit(const vector<int>& prices,int fee)
{
    if(prices.empty())return 0;
    int cash = 0, hold = -prices[0];
    int n = prices.size();
    for(int i = 1; i < n; ++i)
    {
        cash = max(cash,hold + prices[i]-fee);
        hold = max(hold,cash - prices[i]);
    }
    return cash;

}

int maxProfit_cold(vector<int>prices)
{
    if(prices.empty())return 0;
    int n = prices.size();
    if(n < 2)return 0;
    vector<vector<int>>dp(n,vector<int>(2));
    dp[0][0] = 0;
    dp[0][1] = -prices[0];
    dp[1][0] = max(dp[0][0],dp[0][1] + prices[1]);
    dp[1][1] = max(dp[0][1],dp[0][0] - prices[1]);
    for(int i = 2; i < n; ++i)
    {
        dp[i][1] = max(dp[i-1][1],dp[i-2][0]-prices[i]);
        dp[i][0] = max(dp[i-1][0],dp[i-1][1]+prices[i]);
    }
    return dp[n-1][0];
}

int maxProfit123(const vector<int>& prices)
{
    if(prices.empty())return 0;
    int n = prices.size();
    vector<vector<vector<int>>>dp(n,vector<vector<int>>(3,vector<int>(2)));
    dp[0][1][0] = 0;
    dp[0][1][1] = -prices[0];
    dp[0][2][0] = 0;
    dp[0][2][1] = -prices[0];
    for(int i = 1; i < n; ++i)
    {
        for(int k = 2; k >= 1; --k)
        {
            dp[i][k][0] = max(dp[i-1][k][0],dp[i-1][k][1]+prices[i]);
            dp[i][k][1] = max(dp[i-1][k][1],dp[i-1][k-1][0] - prices[i]);
        }
    }
    return dp[n-1][2][0];

}

int maxProfit_K(const vector<int>&prices,int K)
{
    if(prices.empty())return 0;
    int n = prices.size();
    vector<vector<vector<int>>>dp(n,vector<vector<int>>(K+1,vector<int>(2)));
    for(int i = 0; i < n;++i)
    {
        for(int k = K; k >= 1; --k)
        {
            if(i == 0)
            {
                dp[0][k][0] = 0;
                dp[0][k][1] = -prices[0];
                continue;
            }
            dp[i][k][0] = max(dp[i-1][k][0],dp[i-1][k][1]+prices[i]);
            dp[i][k][1] = max(dp[i-1][k][1],dp[i-1][k-1][0]-prices[i]);
        }
    }
    return dp[n-1][K][0];
}

int main()
{
    //LeetCode121
//    vector<int>prices{7,1,5,3,6,4};
//    vector<int>prices{7,6,4,3,1};
//    cout << maxProfit(prices) << endl;
//    cout << maxProfit_greedy(prices) << endl;

    //LeetCode122
//    vector<int>prices{1,2,3,4,5};
//    vector<int>prices{7,1,5,3,6,4};
//    cout << maxProfit_II(prices) <<endl;
//    cout << maxProfit_II_greedy(prices) << endl;

//    //LeetCode714
//    vector<int>prices{1,3,2,8,4,9};
//    int fee = 2;
//    cout << maxprofit(prices,fee) << endl;
//    cout << maxProfit(prices,fee) << endl;


    //LeetCode309
//    vector<int>prices{1,2,3,0,2};
//    prices = {1};
//    cout << maxProfit_cold(prices) << endl;

    //LeetCode123
//    vector<int>prices{3,3,5,0,0,3,1,4};
//    cout << maxProfit_cold(prices) << endl;

    //LeetCode188
    int k = 2;
    vector<int>prices{3,2,6,5,0,3};
    cout << maxProfit_K(prices,k) << endl;
    return 0;
}