I am preparing video tutorials on each problem. Hope it helps people.
1. Link to A-Frog 1:- https://www.youtube.com/watch?v=9yZL_AA9FyY
2. Link to B-Frog 2:- https://www.youtube.com/watch?v=b8zdg91nUys
3. Link to C-Vacation:- https://www.youtube.com/watch?v=jQpBVS_MQqo
4. Link to D-Knapsack 1:- https://www.youtube.com/watch?v=DrkxlK87WxE