30 lines
721 B
C++
30 lines
721 B
C++
//http://contest-hunter.org:83/contest/0x10%E3%80%8C%E5%9F%BA%E6%9C%AC%E6%95%B0%E6%8D%AE%E7%BB%93%E6%9E%84%E3%80%8D%E4%BE%8B%E9%A2%98/1201%20%E6%9C%80%E5%A4%A7%E5%AD%90%E5%BA%8F%E5%92%8C
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#include<cstdio>
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#include<cstring>
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#include<algorithm>
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using namespace std;
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typedef long long LL;
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const int maxn=300005;
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LL res,a[maxn],s[maxn];
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int n,m,q[maxn];
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int main()
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{
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#ifdef local
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freopen("pro.in","r",stdin);
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#endif
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scanf("%d%d",&n,&m);
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for(int i=1;i<=n;i++) scanf("%lld",&a[i]);
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res=a[1];
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int l=1,r=1; q[1]=0;
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for(int i=1;i<=n;i++) s[i]=s[i-1]+a[i];
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for(int i=1;i<=n;i++)
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{
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while(l<=r&&q[l]<i-m) l++;
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res=max(res,s[i]-s[q[l]]);
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while(l<=r&&s[q[r]]>=s[i]) r--;
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q[++r]=i;
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}
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printf("%lld\n",res);
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return 0;
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}
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