3、Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without
repeating letters for "abcabcbb" is "abc", which the length is 3. For "bbbbb" the longest substring is "b", with the length of 1.

Hash
Table Two Pointers String

int lengthOfLongestSubstring(string s) {
int place[128];
for (int i = 0; i < 128; ++i)
place[i] = -1;
int length = s.size();
int maxLength = 0, maxIndex = -1;
for (int i = 0; i < length; ++i)
{
//此方法比较取巧，可能一眼难以理解，此题中关于哈希表的应用也是不大清楚
maxIndex = max(place[s[i]], maxIndex);
maxLength = max(i - maxIndex, maxLength);
place[s[i]] = i;
}
return maxLength;
}