think about the time complexity. Whats the time complexity of the sorting? NlogN And when using hash mapping, it can be only N. Mapping the string to an alphabet array, the index is the char and the value stores the frequency of the char. Hope it helps.

Just reverse one string and then compare the result with other string.

hash

easiest way probably to reduce the characters to ascii, add them all together. If values are equal, they all contain the same characters. O(n)