求最长不重复子串长度,复杂度为O(n²),有待优化
class Solution {
public:
int lengthOfLongestSubstring(string s) {
int maxlen=0,len=s.size();
if(len==0)
{
cout<<"nothing"<<endl;
}
else
if(len==1)
{
maxlen=1;
}
else{
int dp[len+1];
int i,j;
int last_start=0;
dp[0]=1;
for(i=1;i<len;++i)
{
for(j=i-1;j>=last_start;--j)
{
if(s[j]==s[i])
{
dp[i]=i-j;
last_start=j+1;
break;
}
else if(j==last_start)
{
dp[i]=dp[i-1]+1;
}
}
if(dp[i]>maxlen)
{
maxlen=dp[i];
}
}}
return maxlen;
}
};