leetcode：1-5题代码整理
以下是这段时间抽时间刷的前5题，都是自己想的解法，或许不是最优解，只是整理下，方便日后优化提升
1. Two Sum：
class Solution: # @return a tuple, (index1, index2) def twoSum(self, num, target): dict = {} for i in xrange(len(num)): if dict.get(target-num[i], None) == None: dict[num[i]] = i else: return (dict[target-num[i]] , i )
2. Add Two Numbers：
class Solution(object): def addTwoNumbers(self, l1, l2): """ :type l1: ListNode :type l2: ListNode :rtype: ListNode """ more=0 l3=ListNode(0) l3.val=l1.val+l2.val+more if l3.val>=10: more=1 else: more=0 l3.val=l3.val%10 l1_temp=l3 l1=l1.next l2=l2.next while(l1 and l2): temp=ListNode(0) temp.val=l1.val+l2.val+more if temp.val>=10: more=1 else: more=0 temp.val=temp.val%10 l1_temp.next=temp l1_temp=temp l1=l1.next l2=l2.next if((l1 is None )and( l2 is None)): if more==1: temp=ListNode(0) temp.val=1 l1_temp.next=temp return l3 elif(l1 and ( l2 is None)): while(l1): temp=ListNode(0) temp.val=more+l1.val if temp.val>=10: more=1 else: more=0 temp.val=temp.val%10 l1_temp.next=temp l1_temp=temp l1=l1.next if more==1: temp=ListNode(0) temp.val=1 l1_temp.next=temp return l3 elif(l2 and ( l1 is None)): while(l2): temp=ListNode(0) temp.val=more+l2.val if temp.val>=10: more=1 else: more=0 temp.val=temp.val%10 l1_temp.next=temp l1_temp=temp l2=l2.next if more==1: temp=ListNode(0) temp.val=1 l1_temp.next=temp return l3
3. Longest Substring Without Repeating Characters：
class Solution(object): def lengthOfLongestSubstring(self, s): """ :type s: str :rtype: int """ new_str = '' max = 0 for ch in s: if not ch in new_str: new_str += ch else: max = len(new_str) if len(new_str) > max else max idx = new_str.find(ch) new_str = new_str[idx+1:] + ch max = len(new_str) if len(new_str) > max else max return max
4. Median of Two Sorted Arrays：
class Solution(object): def findMedianSortedArrays(self, nums1, nums2): """ :type nums1: List[int] :type nums2: List[int] :rtype: float """ end1=len(nums1)-1 end2=len(nums2)-1 if len(nums1)==0: num=len(nums2) if num%2: #num是一个奇数 return float(nums2[num/2]) else: median=num/2 return (float(nums2[median-1])+nums2[median])/2 elif len(nums2)==0: num=len(nums1) if num%2: #num是一个奇数 median=num/2 return float(nums1[median]) else: median=num/2 return (float(nums1[median-1])+nums1[median])/2 elif nums1[end1]<nums2[0]: nums1.extend(nums2) num=len(nums1) if num%2: #num是一个奇数 median=num/2 return float(nums1[median]) else: median=num/2 return (float(nums1[median-1])+nums1[median])/2 elif nums1[0]>nums2[end2]: nums2.extend(nums1) num=len(nums2) if num%2: #num是一个奇数 return float(nums2[num/2]) else: median=num/2 return (float(nums2[median-1])+nums2[median])/2 else: i=0 j=0 new=[] while i<len(nums1) and j<len(nums2): if nums1[i]<nums2[j]: new.append(nums1[i]) i=i+1 elif nums1[i]==nums2[j]: new.append(nums1[i]) new.append(nums1[i]) i=i+1 j=j+1 else: new.append(nums2[j]) j=j+1 while i<len(nums1): new.append(nums1[i]) i=i+1 while j<len(nums2): new.append(nums2[j]) j=j+1 num=len(new) if num%2: #num是一个奇数 return float(new[num/2]) else: median=num/2 return (float(new[median-1])+new[median])/2
5. Longest Palindromic Substring：
class Solution(object): def longestPalindrome(self, s): """ :type s: str :rtype: str """ if len(s)==1: return s elif len(s)==2 and s[0]==s[1]: return s else: s_fin1="" s_fin2="" index_l=0 index_r=1 max_length=0 left=-1 right=-1 flag=0 while index_r<len(s): i=0 length=0 while index_l-i>=0 and index_r+i<len(s) and s[index_l-i]==s[index_r+i]: i=i+1 length=length+2 if length>max_length: max_length=length left=index_l right=index_r index_l=index_l+1 index_r=index_r+1 if max_length: begin=left-max_length/2+1 end=right+max_length/2 flag=2 s_fin1=s[begin:end] index=1 max_length=1 center=-1 flag=0 while index<(len(s)-1): i=1 length=1 while index-i>=0 and index+i<len(s) and s[index-i]==s[index+i]: i=i+1 length=length+2 if length>max_length: max_length=length center=index index=index+1 if max_length>1: begin=center-(max_length-1)/2 end=center+(max_length-1)/2+1 flag=1 s_fin2=s[begin:end] if len(s_fin1)>len(s_fin2): return s_fin1 else: return s_fin2
