贪心 FZU 2013 A short problem

题目传送门

/*
    题意：取长度不小于m的序列使得和最大
    贪心：先来一个前缀和，只要长度不小于m，从m开始，更新起点k最小值和ans最大值
*/
#include <cstdio>
#include <algorithm>
using namespace std;

const int MAXN = 1e6 + 10;
const int INF = 0x3f3f3f3f;
int a[MAXN], sum[MAXN];

int main(void)        //FZU 2013 A short problem
{
//    freopen ("C.in", "r", stdin);

    int t;    scanf ("%d", &t);
    while (t--)
    {
        int n, m;    scanf ("%d%d", &n, &m);
        for (int i=1; i<=n; ++i)
        {
            scanf ("%d", &a[i]);    sum[i] = sum[i-1] + a[i];
        }

        int k = 0;    int ans = -INF;
        for (int i=m; i<=n; ++i)
        {
            ans = max (ans, sum[i] - k);
            k = min (k, sum[i-m]);
        }

        printf ("%d
", ans);
    }

    return 0;
}