Problem:
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.
思路：
Solution (C++):
int lengthOfLongestSubstring(string s) {
int n = s.length();
if (n == 0) return 0;
int pre = -1, cur_len = 0, len = 0;
unordered_map<char, int> map;
for (auto c : s) map[c] = -1;
for (int i = 0; i < n; ++i) {
pre = max(pre, map[s[i]]);
cur_len = i - pre;
len = max(len, cur_len);
map[s[i]] = i;
}
return len;
}
性能：
Runtime: 32 ms Memory Usage: 8.7 MB
思路：
Solution (C++):
int lengthOfLongestSubstring(string s) {
int n = s.length();
if (n == 0) return 0;
unordered_map<char, int> map;
int len = 0, last_len = 0;
for (auto c : s) map[c] = -1;
for (int i = 0; i < n; ++i) {
if (i - map[s[i]] <= last_len)
last_len = i - map[s[i]];
else
++last_len;
map[s[i]] = i;
len = max(len, last_len);
}
return len;
}
性能：
Runtime: 32 ms Memory Usage: 8.6 MB
