leetcode

start from zero...

338. Counting Bits

https://leetcode.com/problems/counting-bits/description/

Num(n)=the number of 1's in n's binary representation

      Num(n+1)=

                0, if n==0;

                Num(n)+1, if n%2==0;

                Num((n+1)/2), if n%2==1;

Program: Iteration/ Recursion+memo(to be added)

646. Maximum Length of Pair Chain

https://leetcode.com/problems/maximum-length-of-pair-chain/description/

Greedy algorithm solutes easily.

24. Swap Nodes in Pairs

https://leetcode.com/problems/swap-nodes-in-pairs/description/