Please explain the logic for doing this question.

It is based on popularly known dynamic programming problem edit distance.So basically in that problem u can delete replace as well as insert the character.Here is the link where u can find both recursive as well as dp solution.U just need to make few changes the solution in the links assumes equal cost of insert delete and replace operation u need to remove delete operation and also change cost of insert and delete operation and then your code will work fine.

Happy Coding :stuck_out_tongue:
link text

But the accepted solution does not contains this approach.Instead they have iteratively solved it.

for the test 1 abc pcg accepted solutions give O/P 3 but shouldn’t the answer be 1? add g to the end of 1st string and b in the 2nd string between p and c. now the strings become abcg pbcg with cost 0. then change p to a. hence total cost 1.