Leetcode日记8

题干

解法：EZ

class Solution {
public:
    int lengthOfLongestSubstring(std::string s) {
        if(s.size() == 0)  return 0;
        int res = 1;
        int i = 0 , len = 1, mark = 0;
        std::string pos,pre;
        std::unordered_map<std::string, int> hash;
        while(i+len < s.size()){
            pos = s.substr(i,len);
            pre = s.substr(i+len,1);
            std::string in = pos.substr(len-1,1);
            hash[in] = len-1;
            auto it = hash.find(pre);
                if(it != hash.end()){
                    i += hash[pre] + 1;
                    len = 1;
                    pos = s.substr(i,1);
                    hash.clear();
                    continue;
                }
            len++;
            if(len > res) res = len;
        }
    return res;
    }
};

hash表 省时间的神！

一开始做错了 理解错题意 做成字串内不重复了

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        int res = 0;
        int i = 0 , j = 1;
        std::string pos = s.substr(i,1);
        std::string pre = s.substr(i+j,j);
        while(i+j <= s.size()){
            if(pos != pre){
                j++;
                pos = s.substr(i,j);
                if(i+j+j < s.size()){
                    pre = s.substr(i+j,j);  
                }
                else{
                    if(s.size()-i > res) res = s.size()-i;
                    break;
                }
                if(j-1 > res) res = j-1;
                continue;
            }
            else{
                i += j;
                j = 1;
                pos = s.substr(i,j);
                pre = s.substr(i+j,j);
                continue;
            }  
        }
    return res;
    }
};