8000 Longest Substring Without Repeating Characters by LiEmail · Pull Request #64 · soulmachine/leetcode · GitHub
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Longest Substring Without Repeating Characters #64

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Jan 8, 2016
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Longest Substring Without Repeating Characters #64

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9 changes: 5 additions & 4 deletions C++/chapGreedy.tex
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Expand Up @@ -282,21 +282,22 @@ \subsubsection{代码}
\begin{Code}
// LeetCode, Longest Substring Without Repeating Characters
// 时间复杂度O(n)，空间复杂度O(1)
// 考虑非字母的情况
class Solution {
public:
int lengthOfLongestSubstring(string s) {
const int ASCII_MAX = 26;
const int ASCII_MAX = 255;
int last[ASCII_MAX]; // 记录字符上次出现过的位置
int start = 0; // 记录当前子串的起始位置

fill(last, last + ASCII_MAX, -1); // 0也是有效位置，因此初始化为-1
int max_len = 0;
for (int i = 0; i < s.size(); i++) {
if (last[s[i] - 'a'] >= start) {
if (last[s[i]] >= start) {
max_len = max(i - start, max_len);
start = last[s[i] - 'a'] + 1;
start = last[s[i]] + 1;
}
last[s[i] - 'a'] = i;
last[s[i]] = i;
}
return max((int)s.size() - start, max_len); // 别忘了最后一次，例如"abcd"
}
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