@damn_me I am clear with push_back, but I am not very clear with sorting.
https://www.dropbox.com/s/fmass1ub4keixg3/Sorting.cpp?dl=0
I tried the above code to sort based on 1st element, 2nd element and so on.
Input:
3 4 5
2 3 4
1 2 3
1 6 7
1 3 5
Correct output:
1 2 3
1 3 5
1 6 7
2 3 4
3 4 5
My wrong output:
1 2 3
1 2 3
1 2 3
1 2 3
1 2 3
I know the way I have used sort is wrong but I wasn’t able to understand the row number technique you did using map.
Damn me @damn_me 
Now, maps are super new to me, so I am not familiar with any of the operations on map,. But I am able to get the logic now. If it’s trouble demonstrating the map operations in code like how you did for the original question could you please direct me to a resource which explains these operations well? Then, I’ll try sorting using this logic myself and attach the code. My gratitude is inexpressible. Thanks a lottt!
See this, v27HS0 - Online C++ Compiler & Debugging Tool - Ideone.com. Read about maps, iterators and basically STL. it’s really a powerful tool for many operations with less code to type with efficieny as an add-on. See : http://www.cplusplus.com/reference/utility/pair/
http://www.cplusplus.com/reference/map/map/
http://www.cplusplus.com/reference/utility/make_pair/