cf B. Fence
http://codeforces.com/contest/363/problem/B
1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 #define maxn 500001 5 using namespace std; 6 const int inf=1<<30; 7 8 int n,k; 9 int a[maxn]; 10 int min1; 11 int sum[maxn]; 12 13 int main() 14 { 15 while(scanf("%d%d",&n,&k)!=EOF) 16 { 17 min1=inf; 18 sum[0]=0; 19 for(int i=1; i<=n; i++) 20 { 21 scanf("%d",&a[i]); 22 sum[i]=sum[i-1]+a[i]; 23 } 24 int c=1; 25 for(int i=1; i<=n; i++) 26 { 27 if(sum[i+k-1]-sum[i-1]<min1&&i+k-1<=n) 28 { 29 c=i; 30 min1=sum[i+k-1]-sum[i-1]; 31 } 32 } 33 printf("%d\n",c); 34 } 35 return 0; 36 }