Given a string, find the length of the longest substring without repeating characters.
(给定一个字符串,找字符中的最大非重复子串)
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.
首先,这道题目要求是“非重复最长子串”,所以我们应该在第一时间点想到用HashSet容器。
其次,我们用两个指针,一个遍历数组,另一个检测是否有重复的字符。如果发现重复字符,则remove。
最后用Math.max()函数记录最大的长度即可。
Java实现代码如下:
class Solution {
public int lengthOfLongestSubstring(String s) {
int res = 0;
if (s == null || s.length() == 0) return res;
//注意区别字符串的length()方法与数组的length属性
HashSet<Character> set = new HashSet<>();
for (int i = 0, j = 0; i < s.length();) {
if (set.contains(s.charAt(i))) {
set.remove(s.charAt(j++));
} else {
set.add(s.charAt(i++));
res = Math.max(res, set.size());
}
}
return res;
}
}