Daliy Algorithm (dp，数学，贪心)-- day 78

Nothing to fear

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种一棵树最好的时间是十年前，其次是现在！

那些你早出晚归付出的刻苦努力，你不想训练，当你觉的太累了但还是要咬牙坚持的时候，那就是在追逐梦想，不要在意终点有什么，要享受路途的过程，或许你不能成就梦想，但一定会有更伟大的事情随之而来。 mamba out~

2020.5.14

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人一我十，人十我百，追逐青春的梦想，怀着自信的心，永不言弃！

lc-面试题63. 股票的最大利润

找到最小得哪个点买入，每次遇到一个比它价格高得就计算和之前相比所能得到得最大利润

class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        if len(prices) == 0:
            return 0
        price , profit = prices[0] , 0
        for i in range(len(prices)):
            if prices[i] < price:
                price = prices[i]
            else:
                profit = max(prices[i] - price,profit)
        return profit

lc-523. 连续的子数组和

我还以为我想到得(O(n^{2}))的解法也过不了呢 不得不说评测鸡真好 10^8搁在别的地方大概率是通过不了的吧,就这题通过率还这么低，不过还是有一些小坑点

class Solution:
    def checkSubarraySum(self, nums: List[int], k: int) -> bool:
        n = len(nums)
        if n == 0:
            return False
        prefix = [0 for _ in range(n)]
        prefix[0] = nums[0]
        for i in range(1,n):
            prefix[i] = prefix[i-1] + nums[i]
        for i in range(n):
            for j in range(i+1,n):
                sumc = prefix[j]-prefix[i]+nums[i]
                if sumc == k or (k != 0 and sumc % k == 0):
                    return True
        return False

对于前三题做题慢得主要原因就是读题太慢了 还老是读错题意，我这蹩脚得英语 唉~
剩下得后面补题吧 太困了

CF642-A

思维

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <cassert>
#include <string>
#include <iomanip>
#include <cmath>
#include <ctime>
#define SIS std::ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
#define lowbit(x) (x & -x)
using namespace std;
typedef long long ll;
const int MAX = 0x7ffffff;
int t;

void slove()
{
    int n , m;
    cin >> n >> m;
    if(n == 1)
    {
        cout << 0 << endl;
    }
    if(n == 2)
    {
        cout << m << endl;
    }
    if(n >= 3)
    {
        cout << 2 * m << endl;
    }
    return ;
}
int main()
{
#ifdef LOCAL
    auto start_time = clock();
    cerr << setprecision(3) << fixed; // 在iomanip中
#endif
    SIS;
    cin >> t;
    while(t--)
    {
        slove();
    }
#ifdef LOCAL
    auto end_time = clock();
    cerr << "Execution time: " << (end_time - start_time) * (int)1e3 / CLOCKS_PER_SEC << " ms
";
#endif
}

B

排序 ， 贪心

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <cassert>
#include <string>
#include <iomanip>
#include <cmath>
#include <ctime>
#define SIS std::ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
#define lowbit(x) (x & -x)
using namespace std;
typedef long long ll;
const int MAX = 0x7ffffff;
int t;

void slove()
{
    int n , k;
    cin >> n >> k;
    vector<int> a(n + 1) , b(n + 1);
    for(int i = 1;i <= n ;i ++)cin >> a[i];
    for(int i = 1;i <= n ;i ++)cin >> b[i];
    sort(a.begin(),a.end());
    sort(b.begin(),b.end());
    ll sum = 0;
    int i = 1 ,j = n;
    while(k--)
    {
        if(a[i] < b[j])
        {
            swap(a[i],b[j]);
            i++;j--;
        }
    }
    for(i = 1; i <= n ;i ++)sum += a[i];
    cout << sum << endl;
}
int main()
{
#ifdef LOCAL
    auto start_time = clock();
    cerr << setprecision(3) << fixed; // 在iomanip中
#endif
    SIS;
    cin >> t;
    while(t--)
    {
        slove();
    }
#ifdef LOCAL
    auto end_time = clock();
    cerr << "Execution time: " << (end_time - start_time) * (int)1e3 / CLOCKS_PER_SEC << " ms
";
#endif
}

C

数学

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <cassert>
#include <string>
#include <iomanip>
#include <cmath>
#include <ctime>
#define SIS std::ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
#define lowbit(x) (x & -x)
using namespace std;
typedef long long ll;
const int MAX = 0x7ffffff;
int t;

void slove()
{
    int n;
    cin >> n;
    ll ans = 0;
    for(int i = 1;i <= n / 2; i ++)
    {
        ans += i * 1ll * i;
    }
    cout << ans * 8 << endl;
}
int main()
{
#ifdef LOCAL
    auto start_time = clock();
    cerr << setprecision(3) << fixed; // 在iomanip中
#endif
    SIS;
    cin >> t;
    while(t--)
    {
        slove();
    }
#ifdef LOCAL
    auto end_time = clock();
    cerr << "Execution time: " << (end_time - start_time) * (int)1e3 / CLOCKS_PER_SEC << " ms
";
#endif
}