// 单调队列 int l = 1, r = 1; q[1] = 0; // save choice j=0 for(int i = 1; i <= n; i++) { while (l <= r && q[l] < i - m) l++; ans = max(ans, sum[i] - sum[q[l]]); while (l <= r && sum[q[r]] >= sum[i]) r--; q[++r] = i; }