CodeChef Code SGARDEN

This time Sheriff gathered all the bandits in his garden and ordered them to line up. After the whistle all bandits should change the order in which they stand.
Sheriff gave all the bandits numbers from 1 to N. For each place i he determined the unique position j. After whistling the bandit staying on position i should run to the j-th position. Sheriff loved seeing how the bandits move around, and he continued whistling until the evening. He finished the game only when he noticed that the bandits are in the same order in which they were standing originally.
Now the Sheriff asks the question: How many times has he whistled?

Length of the longest substring without repeating characters

Length of the longest substring without repeating characters

Method 1 (Brute Force Method)
We can consider all substrings.
One by one and check for each substring whether it contains all unique characters or not. 
There will be n*(n+1)/2 substrings.