贪心 FZU 2013 A short problem

 1 /*
 2     题意：取长度不小于m的序列使得和最大
 3     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
 4 */
 5 #include <cstdio>
 6 #include <algorithm>
 7 using namespace std;
 8 
 9 const int MAXN = 1e6 + 10;
10 const int INF = 0x3f3f3f3f;
11 int a[MAXN], sum[MAXN];
12 
13 int main(void)        //FZU 2013 A short problem
14 {
15 //    freopen ("C.in", "r", stdin);
16 
17     int t;    scanf ("%d", &t);
18     while (t--)
19     {
20         int n, m;    scanf ("%d%d", &n, &m);
21         for (int i=1; i<=n; ++i)
22         {
23             scanf ("%d", &a[i]);    sum[i] = sum[i-1] + a[i];
24         }
25 
26         int k = 0;    int ans = -INF;
27         for (int i=m; i<=n; ++i)
28         {
29             ans = max (ans, sum[i] - k);
30             k = min (k, sum[i-m]);
31         }
32 
33         printf ("%d\n", ans);
34     }
35 
36     return 0;
37 }