competitive-programming Link of training sites: https://www.codewars.com/ https://www.codechef.com https://www.codefights.com Resource MIT Course https://www.youtube.com/watch?v=HtSuA80QTyo&list=PLUl4u3cNGP61Oq3tWYp6V_F-5jb5L2iHb https://www.youtube.com/watch?v=2P-yW7LQr08&list=PLUl4u3cNGP6317WaSNfmCvGym2ucw3oGp Tutorials http://vnoi.info/wiki/algo/data-structures/segment-tree-extend