3. 無重複字元的最長子串

示例1:

輸入: s = "abcabcbb"
輸出: 3 
解釋: 因為無重複字元的最長子串是 "abc"，所以其長度為 3。

示例 2:

輸入: s = "bbbbb"
輸出: 1
解釋: 因為無重複字元的最長子串是 "b"，所以其長度為 1。

示例 3:

輸入: s = "pwwkew"
輸出: 3
解釋: 因為無重複字元的最長子串是"wke"，所以其長度為 3。
    請注意，你的答案必須是 子串 的長度，"pwke"是一個子序列，不是子串。

提示：

• 0 <= s.length <= 5 * 104
• s由英文字母、數字、符號和空格組成

 1 #include <iostream>
 2 #include <unordered_map>
 3 
 4 using namespace std;
 5 
 6 class Solution {
 7 public:
 8     int lengthOfLongestSubstring(string s) {
 9         if (s.size() == 0) {
10             return 0;
11         }
12         unsigned int start = 0;
13         unsigned int
 
 end = 0;
14         unsigned int maxSubStrNum = 0;
15         unordered_map<char, unsigned int> hashMap; // key->字元, value->字元位置
16         for (; end < s.size(); end++) {
17             unordered_map<char, unsigned int>::iterator it;
18             it = hashMap.find(s[end]);
19             if
 
 (it != hashMap.end()) {
20                 start = std::max(it->second + 1, start);
21             }
22             maxSubStrNum = std::max(maxSubStrNum, end - start + 1);
23             hashMap[s[end]] = end;
24         }
25         return maxSubStrNum;
26     }
27 };
28 
29 int main()
30 {
31     Solution *test = new Solution();
32     string s = "abcabcbb";
33     std::cout << "s: " << s << endl;
34     std::cout << "maxSubstringLen:"<< test->lengthOfLongestSubstring(s) << endl; // 3
35 
36     s = "";
37     std::cout << "s: " << s << endl;
38     std::cout << "maxSubstringLen:"<< test->lengthOfLongestSubstring(s) << endl; // 0
39 
40     s = "bbbb";
41     std::cout << "s: " << s << endl;
42     std::cout << "maxSubstringLen:"<< test->lengthOfLongestSubstring(s) << endl; // 1
43 
44     s = "pwwkew";
45     std::cout << "s: " << s << endl;
46     std::cout << "maxSubstringLen:"<< test->lengthOfLongestSubstring(s) << endl; // 3
47 
48     delete test;
49     system("pause");
50     return 0;
51 }