題意：給出一個數列，需要找出k個連續欄位，讓他們的和最大。

題解：動態規劃，首先可以假設 $dp\left[i\right]\left[j\right]$

$ac\ code:$

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define met(a, b) memset(a, b, sizeof(a))
#define rep(i, a, b) for(int i = a; i <= b; i++)
#define per(i, a, b) for(int i = a; i >= b; i--)
#define MAXSIZE 10
#define DLEN 4
const int maxn = 1e5 + 10;
const int inf = 0x3f3f3f3f;

class Kattis_maximumsubarrays {
public:
    Kattis_maximumsubarrays();
    ~Kattis_maximumsubarrays();
    void input();
    void init();
    void solve();
private:
    ll *dp, *MAX, *a;
    int n, m;
};

int main() {
    Kattis_maximumsubarrays * pro = new Kattis_maximumsubarrays();
    pro -> solve();
    delete pro;
    pro = NULL;
    return 0;
}
Kattis_maximumsubarrays::Kattis_maximumsubarrays() {
    dp = new ll[maxn];
    MAX = new ll[maxn];
    a = new ll[maxn];
}

Kattis_maximumsubarrays::~Kattis_maximumsubarrays() {
    delete []dp;
    delete []MAX;
    delete []a;
    dp = NULL;
    MAX = NULL;
    a = NULL;
}
void Kattis_maximumsubarrays::input() {
    scanf("%d%d", &n, &m);
    rep(i, 1, n) {
        scanf("%lld", &a[i]);
    }
}

void Kattis_maximumsubarrays::init() {
    for(int i = 0; i < maxn;i ++) dp[i] = MAX[i] = 0;
}

void Kattis_maximumsubarrays::solve() {
    init();
    input();
    ll ans = -1e18;
    rep(i, 1, m) {
        ans = -1e18;
        rep(j, i, n) {
            dp[j] = max(dp[j - 1] + a[j], MAX[j - 1] + a[j]);
            MAX[j - 1] = ans;
            ans = max(ans, dp[j]);
        }
    }
    printf("%lld\n", ans);
}