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 + ;
 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=; i<=n; ++i)
         {
             scanf ("%d", &a[i]);    sum[i] = sum[i-] + a[i];
         }

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

         printf ("%d\n", ans);
     }

     return ;
 }