[LeetCode]#1356. Sort Integers by The Number of 1 Bits
2 min readJan 13, 2021
Environment: Python 3.8
Key technique: bin(), lambda
Given an integer array arr. You have to sort the integers in the array in ascending order by the number of 1's in their binary representation and in case of two or more integers have the same number of 1's you have to sort them in ascending order.
Return the sorted array.
Example 1:
Input: arr = [0,1,2,3,4,5,6,7,8]
Output: [0,1,2,4,8,3,5,6,7]
Explantion: [0] is the only integer with 0 bits.
[1,2,4,8] all have 1 bit.
[3,5,6] have 2 bits.
[7] has 3 bits.
The sorted array by bits is [0,1,2,4,8,3,5,6,7]Example 2:
Input: arr = [1024,512,256,128,64,32,16,8,4,2,1]
Output: [1,2,4,8,16,32,64,128,256,512,1024]
Explantion: All integers have 1 bit in the binary representation, you should just sort them in ascending order.Example 3:
Input: arr = [10000,10000]
Output: [10000,10000]Example 4:
Input: arr = [2,3,5,7,11,13,17,19]
Output: [2,3,5,17,7,11,13,19]Example 5:
Input: arr = [10,100,1000,10000]
Output: [10,100,10000,1000]Analysis:
- Convert arr to bit format.
- count(‘1') in each arr
- sort it by step 2 red mark value
- return blue mark value
Solution:
class Solution:
def sortByBits(self, arr):
d=[]
for i in sorted(arr):
d.append((i,bin(i).count('1')))sd = sorted(d, key=lambda i: i[1])ans=[]
for i in sd:
ans.append(i[0])
return ans
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