string caseout = "";1.读入测试用例字符串casein2.如果对应语言有Init()函数的话，执行Init() 函数3.循环遍历字符串里的每一个字符ch {Insert(ch);caseout += FirstAppearingOnce()}2. 输出caseout，进行比较。
如果当前字符流没有存在出现一次的字符，返回#字符。
"google"
"ggg#ll"
"abcdee"
"aaaaaa"
class Solution:
def __init__(self):
self.ListA = []
def FirstAppearingOnce(self):
self.dictB = {}
for i in self.ListA:
if i not in self.dictB.keys():
self.dictB[i] = 1
else:
self.dictB[i] += 1
for a in self.ListA:
if self.dictB[a] == 1:
return a
return '#'
def Insert(self, char):
self.ListA.append(char) 
# -*- coding:utf-8 -*-
from collections import Counter
class Solution:
def __init__(self):
self.s=''
#self.dict={} #创建字典，key为读取的字符串中的每一个字符，val为每个字符出现的个数的计数值
# 返回对应char
def FirstAppearingOnce(self):
dic=Counter(self.s)
for i in dic:
if dic[i]==1:
return i
return "#"
def Insert(self, char):
# write code here
self.s=self.s+char #从字符流中读入字符到字符串s中
为啥显示答案错误啊？
# -*- coding:utf-8 -*-
class Solution:
# 返回对应char
def __init__(self):
self.s = ""
self.dict = {}
def FirstAppearingOnce(self):
for i in self.s:
if self.dict[i] == 1:
return i
return '#'
def Insert(self, char):
# write code here
self.s = self.s + char
if char in self.dict :
self.dict[char] = self.dict[char]+1
else:
self.dict[char] = 1 函数Insert（）中的char等同于函数FirstAppearingOnce（）中的i
# -*- coding:utf-8 -*- class Solution: # 返回对应char def __init__(self): self.s = '' def FirstAppearingOnce(self): # write code here for i in self.s: if self.s.count(i) == 1: return i return '#' def Insert(self, char): # write code here self.s += char直接用count函数判断输出
# -*- coding:utf-8 -*-
# -*- coding:utf-8 -*-
class Solution:
def __init__(self):
self.num_dict = {}
self.first = []
# 返回对应char
def FirstAppearingOnce(self):
# write code here
if len(self.first) == 0:
return '#'
else:
return self.first[0]
def Insert(self, char):
# write code here
if char not in self.num_dict:
self.num_dict[char] = 1
self.first.append(char)
else:
self.num_dict[char] += 1
if self.num_dict[char]==2:
for i in range(len(self.first)):
if char==self.first[i]:
self.first.pop(i)
break
利用一个字典，记录每个字符的数量，一个数组记录为1的字符。插入一个字符，用字典判断该字符的数量，如果字典中不存在该字符，则该字符分别插入字典和数组。如果该字符已经存在,并且数量为1，那么在数组中查找该字符，并且弹出。字典中数量加1# -*- coding:utf-8 -*- class Solution: def __init__(self): self.outp='' self.str1=[] self.occured=[] self.char='' # 返回对应char def FirstAppearingOnce(self): if self.str1==[]: self.str1.append(self.char) self.outp=self.char return self.outp if self.char!=self.outp: self.str1.append(self.char) return self.outp if self.char==self.outp: self.str1.append(self.char) for i in range(len(self.str1)): c=self.str1.count(self.str1[i]) if c==1: self.outp=self.str1[i] return self.outp if i==len(self.str1)-1: self.str1=[] return '#' def Insert(self, char): self.char=char只有当输出发生变化时才寻找下一个第一个出现的字符
# -*- coding:utf-8 -*- class Solution: # 返回对应char def __init__(self): self.s = [] def FirstAppearingOnce(self): # write code here if len(self.s) == 0: return '#' d = dict() #无序字典，不按照输入的顺序 for x in self.s: if x in d: d[x] += 1 else: d[x] = 1 for x in self.s: # 按照输入的顺序查找 if d[x]==1: return x return '#' def Insert(self, char): # write code here self.s.append(char)
# -*- coding:utf-8 -*-
"""
空间换时间
"""
class Solution:
def __init__(self):
self.data = []
def FirstAppearingOnce(self):
"""
Time: O(n)
space: O(1)
:return:
"""
cnt = {}
for d in self.data:
cnt[d] = cnt.get(d,0) + 1
for d in self.data:
if cnt[d] == 1:
return d
return "#"
def Insert(self, char):
self.data.append(char)
s = Solution()
s.Insert("g")
s.Insert("o")
s.Insert("o")
s.Insert("g")
s.Insert("g")
ans = s.FirstAppearingOnce()
print(ans)
# -*- coding:utf-8 -*-
class Solution:
def __init__(self):
self.s=''
self.dict={} #创建字典，key为读取的字符串中的每一个字符，val为每个字符出现的个数的计数值
# 返回对应char
def FirstAppearingOnce(self):
# write code here
for i in self.s: #遍历字符串s中的字符
if self.dict[i]==1: #如果某个字符对应的计数为1，则返回该字符
return i
return '#' #在所有字符遍历完后，进行判断
def Insert(self, char):
# write code here
self.s=self.s+char #从字符流中读入字符到字符串s中
if char in self.dict:
self.dict[char]=self.dict[char]+1 #如果读入的字符在字符串中已存在，在字典中对应的字符计数加一
else:
self.dict[char]=1#如果读入的字符在字符串中不存在，则字典中对应的字符计数为一（即新增了一个新的字符）
本题主要在于理解题意，本题的关键是分两部分，一个是原有字符串的添加，另一个是找到现有字符串中第一次只出现一次的字符
# -*- coding:utf-8 -*-
class Solution:
# 返回对应char
def __init__(self):
self.dict = {}
self.list = []
def FirstAppearingOnce(self):
# write code here
if len(self.list) == 0:
return '#'
else:
for i in self.list:
if self.dict[i] == 1:
return i
return '#'
def Insert(self, char):
# write code here
self.list.append(char)
if char in self.dict:
self.dict[char] = self.dict[char] + 1
else:
self.dict[char] = 1 # -*- coding:utf-8 -*- class Solution: # 返回对应char def __init__(self): self.c = "" def FirstAppearingOnce(self): for s in self.c: if self.c.count(s) == 1: return s return "#" def Insert(self, char): self.c = self.c + char #读入字符到字符串c中
# -*- coding:utf-8 -*- class Solution: def __init__(self): self.s = '' # 返回对应char def FirstAppearingOnce(self): # write code here ls = list(filter(lambda x: self.s.count(x) == 1, self.s )) return ls[0] if ls else '#' def Insert(self, char): # write code here self.s += char
# -*- coding:utf-8 -*-
class Solution():
# 返回对应char
def __init__(self):
self.list01=[]
self.dict01={}
def FirstAppearingOnce(self):
for i in self.list01:
if self.dict01[i]==1:
return i
return '#'
def Insert(self, char):
self.dict01.setdefault(char,0)
self.dict01[char]+=1
if char not in self.list01:
self.list01.append(char) # -*- coding:utf-8 -*- class Solution: # 返回对应char def __init__(self): self.s = '' def FirstAppearingOnce(self): # write code here for i in range(len(self.s)): if self.s.count(self.s[i]) == 1: return self.s[i] return '#' def Insert(self, char): # write code here self.s += char
class Solution: def __init__(self): self.re=[0 for x in range(129)] self.data=[] def FirstAppearingOnce(self): while self.data : f=ord(self.data[0]) if self.re[f]==1: return self.data[0] else: self.data.pop(0) return '#' def Insert(self, char): d=ord(char) self.re[d]+=1 if self.re[d]==1: self.data.append(char)
class Solution: # 返回对应char def __init__(self): self.res = [] def FirstAppearingOnce(self): # write code here if not self.res: #如果res为空 则说明字符流中不存在只出现一次的字符 return '#' return self.res[0] #return 第一个只出现一次的字符 def Insert(self, char): # write code here tmp = self.res if char not in tmp: tmp.append(char) #如果tmp中没有这个字符 将字符导入res中 else: tmp.remove(char) #如果tmp中已经有了该字符 将res中的该字符删除 self.res = tmp[:] #深拷贝我自认位这种方式比书上好理解一点
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//Insert one char from stringstream
private int[] occurence = new int[256];
private int index;
public Solution(){
for(int i=0;i<256;i++){
occurence[i] = -1;
}
index = 0;
}
void Insert(char ch)
{
if(occurence[ch] == -1)
occurence[ch] = index;
else if(occurence[ch] >= 0)
occurence[ch] = -2;
index++;
}
//return the first appearence once char in current stringstream
char FirstAppearingOnce()
{
char ch = '\0';
int minIndex = Integer.MAX_VALUE;
for(int i=0;i<256;i++){
if(occurence[i] >=0 && occurence[i]<minIndex){
ch = (char)i;
minIndex = occurence[i];
}
}
if(ch == '\0')
return '#';
return ch;
}
}