[leetcode]3.longest substring without repeating characters
2016-11-01 10:41
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题目:
Given a string, find the length of the longest substring without repeating characters.
Examples:
Given
which the length is 3.
Given
with the length of 1.
Given
with the length of 3. Note that the answer must be a substring,
a subsequence and not a substring.
解题思路:
1.构造一个滑动框,保证框里面的substring没有重复的字符
2.构造一个长度为256的bool型数组作为标志位,如果在滑动框里面的substring,对应的ascii码的标志位为true
代码如下:
class Solution {
public:
int lengthOfLongestSubstring(string s) {
int length = s.length();
if((length == 0) || (length ==1))
return length;
bool flag[256] = {false};
int count = 0;
int max_count = 0;
int left = 0;
for(int i=0; i<length; i++)
{
char current = s[i];
if(flag[current] == false)
{
flag[current] = true;
count ++;
}
else
{
max_count = max(max_count, i-left);
for(int j=left; j<i; j++)
{
if(s[j] == s[i])
{
left = j+1;
break;
}
else
{
count --;
flag[s[j]] = false;
}
}
}
}
return max(max_count,count);
}
};
Given a string, find the length of the longest substring without repeating characters.
Examples:
Given
"abcabcbb", the answer is
"abc",
which the length is 3.
Given
"bbbbb", the answer is
"b",
with the length of 1.
Given
"pwwkew", the answer is
"wke",
with the length of 3. Note that the answer must be a substring,
"pwke"is
a subsequence and not a substring.
解题思路:
1.构造一个滑动框,保证框里面的substring没有重复的字符
2.构造一个长度为256的bool型数组作为标志位,如果在滑动框里面的substring,对应的ascii码的标志位为true
代码如下:
class Solution {
public:
int lengthOfLongestSubstring(string s) {
int length = s.length();
if((length == 0) || (length ==1))
return length;
bool flag[256] = {false};
int count = 0;
int max_count = 0;
int left = 0;
for(int i=0; i<length; i++)
{
char current = s[i];
if(flag[current] == false)
{
flag[current] = true;
count ++;
}
else
{
max_count = max(max_count, i-left);
for(int j=left; j<i; j++)
{
if(s[j] == s[i])
{
left = j+1;
break;
}
else
{
count --;
flag[s[j]] = false;
}
}
}
}
return max(max_count,count);
}
};
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