HackerRank problems and doubt

#1


This problem is under the the filter search ,But I cannot makeout how to apply binary search on it.please help.

SIr I am a begginner and am getting stuck on many problems .How nmany minimum roblrms should I practice per day so that within 6 month I am very good as competitive programming and can increase my rating on the codechef and codeforces.

#2

I think a lot but did not get the binary search solution for this problem

it can be solved using BFS (breath first search)
here is my code

#3

Can you please show me the working and explanation.

#4

i have shared the whole code