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1404. Number of Steps to Reduce a Number in Binary Representation to One
給定一串表示二進位數字的字串
你可對此字串進行兩項操作:+1跟/2
請透過兩項操作將字串變成1
回傳將字串變成1的所需步驟數
Example 1:
Input: s = "1101"
Output: 6
Explanation: "1101" corressponds to number 13 in their decimal representation.
Step 1) 13 is odd, add 1 and obtain 14.
Step 2) 14 is even, divide by 2 and obtain 7.
Step 3) 7 is odd, add 1 and obtain 8.
Step 4) 8 is even, divide by 2 and obtain 4.
Step 5) 4 is even, divide by 2 and obtain 2.
Step 6) 2 is even, divide by 2 and obtain 1.
Example 2:
Input: s = "10"
Output: 1
Explanation: "10" corressponds to number 2 in their decimal representation.
Step 1) 2 is even, divide by 2 and obtain 1.
Example 3:
Input: s = "1"
Output: 0
Constraints:
1 <= s.length <= 500
s consists of characters '0' or '1'
s[0] == '1'
思路:
模擬 應該有數學解 不過我想不出來 哇哇嗚嗚嗚
Python Code:
class Solution:
def numSteps(self, s: str) -> int:
count = 0
while True:
if s == "1":
return count
if "1" not in s[1:]:
return count+len(s)-1
if s[-1] == "1":
s = str(bin(int(s,2)+1)[2:])
count += 1
else:
s = s[:-1]
count += 1
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