最大子序和
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
1 FOR(i,1,n) sum[i]=sum[i-1]+a[i]; 2 int l=1,r=1; 3 q[1]=0; 4 FOR(i,1,n) 5 { 6 while(l<=r&&q[l]<i-m) l++; 7 ans=max(ans,sum[i]-sum[q[l]]); 8 while(l<=r&&sum[q[r]]>=sum[i]) r--; 9 q[++r]=i; 10 }