LC 3. Longest Substring Without Repeating Characters
题目描述
Given a string, find the length of the longest substring without repeating characters.
Example 1:
Input: "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.
Example 2:
Input: "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.
Example 3:
Input: "pwwkew" Output: 3 Explanation: 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.
参考答案
1 class Solution { 2 public: 3 int lengthOfLongestSubstring(string s) { 4 5 unordered_map<char,int> map; 6 int res = 0; 7 int start = -1; // 存储开始的位置，如果完全没有重复的字符，那么开始位置永远是-1 8 9 for(int i = 0;i<s.length();i++){ 10 if(map.find(s[i]) != map.end()){ 11 start = max(start,map[s[i]]); 12 // 如果通过find 找到了一个重复的 13 // 那么就把start给替换成 上一个重复字符的index 14 } 15 map[s[i]] = i; // map[char] = index; 16 res = max(res,i-start); // 获得最大值 17 } 18 return res; 19 } 20 };
Given a string, find the length of the longest substring without repeating characters.
Example 1:
Input: "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.
Example 2:
Input: "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.
Example 3:
Input: "pwwkew" Output: 3 Explanation: 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.
