代码1
j在i之前，遇到一个重复的就一直增加j，直到j等于i
Runtime: 4 ms, faster than 89.11% of Java online submissions for Longest Substring Without Repeating Characters.
class Solution {
public int lengthOfLongestSubstring(String s) {
int[] arr = new int[256];
int length = 0;
for (int i = 0, j = 0; i < s.length(); i++) {
arr[s.charAt(i)]++;
while (arr[s.charAt(i)] > 1) {
arr[s.charAt(j++)]--;
}
length = Math.max(length, i - j + 1);
}
return length;
}
}
