If you have a sorted array you can find such a pair in O(n) by moving two pointers toward the middle i = 0 j = n-1 while(i < j){ if (a[i] + a[j] == target) return (i, j); else if (a[i] + a[j] < target) i += 1; else if (a[i] + a[j] > … Read more
The database layout should not change when you add more data to it, so the user data should definitely be in one table. Also: Having multiple tables means that you have to create queries dynamically. The cached query plan for one table won’t be used for any other of the tables. Having a lot of … Read more
I don’t believe there are any performance gains from using a readonly field. It’s simply a check to ensure that once the object is fully constructed, that field cannot be pointed to a new value. However “readonly” is very different from other types of read-only semantics because it’s enforced at runtime by the CLR. The … Read more
Never call DataFrame.append or pd.concat inside a for-loop. It leads to quadratic copying. pd.concat returns a new DataFrame. Space has to be allocated for the new DataFrame, and data from the old DataFrames have to be copied into the new DataFrame. Consider the amount of copying required by this line inside the for-loop (assuming each … Read more
Just so we can end this already, here is the answer. Using timeit on my computer we get the results as… Do the multiplication in the loop every time: $ python -m timeit ‘for _ in xrange(10): 10 * 20 > 0’ 1000000 loops, best of 3: 1.3 usec per loop Do the multiplication outside … Read more