[英]Complexity for two approaches of finding next biggest palindrome of a number
我在網上提出了有關下一個最大回文數的問題,並且我已經通過python中的兩種不同方法解決了該問題。 第一個是
t = long(raw_input())
for i in range(t):
a = (raw_input())
a = str(int(a) + 1)
palin = ""
oddOrEven = len(a) % 2
if oddOrEven:
size = len(a) / 2
center = a[size]
else:
size = 0
center = ''
firsthalf = a[0 : len(a)/2]
secondhalf = firsthalf[::-1]
palin = firsthalf + center + secondhalf
if (int(palin) < int(a)):
if(size == 0):
firsthalf = str(int(firsthalf) + 1)
secondhalf = firsthalf[::-1]
palin = firsthalf + secondhalf
elif(size > 0):
lastvalue = int(center) + 1
if (lastvalue == 10):
firsthalf = str(int(firsthalf) + 1)
secondhalf = firsthalf[::-1]
palin = firsthalf + "0" + secondhalf
else:
palin = firsthalf + str(lastvalue) + secondhalf
print palin
另一個是
def inc(left):
leftlist=list(left)
last = len(left)-1
while leftlist[last]=='9':
leftlist[last]='0'
last-=1
leftlist[last] = str(int(leftlist[last])+1)
return "".join(leftlist)
def palin(number):
size=len(number)
odd=size%2
if odd:
center=number[size/2]
else:
center=''
print center
left=number[:size/2]
right = left[::-1]
pdrome = left + center + right
if pdrome > number:
print pdrome
else:
if center:
if center<'9':
center = str(int(center)+1)
print left + center + right
return
else:
center = '0'
if left == len(left)*'9':
print '1' + (len(number)-1)*'0' + '1'
else:
left = inc(left)
print left + center + left[::-1]
if __name__=='__main__':
t = long (raw_input())
while t:
palin(raw_input())
t-=1
從計算機科學的角度來看,這兩種算法的復雜性是什么? 哪個更有效?
我看到您正在for循環中創建一個子列表,並且最大的子列表的大小為n-1。 然后循環到n。
因此,兩者的最壞情況是O(n ^ 2),其中n是t的長度。
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