Counting Bits

Author: Wisteli-ShikhaPandey

Dynamic-Programming/338-Counting-Bits.py

@@ -0,0 +1,41 @@
+'''Leetcode- https://leetcode.com/problems/counting-bits/ '''
+'''
+Given an integer n, return an array ans of length n + 1 such that for each i (0 <= i <= n), ans[i] is the number of 1's in the binary representation of i.
+
+Example 1:
+
+Input: n = 2
+Output: [0,1,1]
+Explanation:
+0 --> 0
+1 --> 1
+2 --> 10
+'''
+
+# Bit manipulation approach
+defcountBits(self, n):
+ans= []
+foriinrange(n+1):
+cur=0
+whilei:
+cur+=i&1
+i>>=1
+ans.append(cur)
+returnans
+
+# T:O(NlogN)
+# S:O(N)
+
+#DP way
+defcountBits(self, n):
+dp= [0]*(n+1)
+offset=0
+
+foriinrange(1,n+1):
+ifoffset*2==i:
+offset=i
+dp[i] =1+dp[i-offset]
+returndp
+
+# T:O(N)
+# S:O(N)

README.md

@@ -26,4 +26,5 @@ Check the notes for the explaination - [Notes](https://stingy-shallot-4ea.notion
 -[x][Climbing Stairs](Dynamic-Programming/70-Climbing-Stairs.py)
 -[x][Maximum Subarray](Dynamic-Programming/53-maximum-subarray.py)
 -[x][Range Sum Query - Immutable](Dynamic-Programming/303-Range-Sum-Query-Immutable.py)
+-[x][Counting Bits](Dynamic-Programming/338-Counting-Bits.py)