Editorial
Need a hint? Checkout the editorial.
View Editorial
Editorial
- Consider Parthib and Abdur Rahman as the same letter $a$ of a string.
- Let the string be $aabcdef$.
- Now count its permutation.
There are $7$ participants in a race. $2$ of the participants are Parthib and Abdur. How many outcomes are possible if we know that Abdur finished ahead of Parthib?