Two Sum II – Input array is sorted
Fraction to Recurring Decimal Use a hash table to track remainders, stop when the remainder is repeated. Be careful on the integer overflow.
Max Points on a Line Check points based on slopes. The trick is to create a key to denote the slope. Double is not doable due to the accuracy.
Pascal’s Triangle II. Not sure if there is a better one, I solve this problem using exactly the same solution as I have in Pascal’s Triangle.
Pascal’s Triangle. Just general Pascal’s triangle row by row, based the Math definition.
Ugly Number. Simply remove those factors and check if the remaining is 1.