LEETCODE 3

Joined
Jun 22, 2024
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can someone tell me what is wrong with my code, i know there are some useless variables, but i can t figure out what is wrong.
it is the third problem in leetcode and it asks:"Given a string s, find the length of the longest
substring
without repeating characters.". This is my code:

class Solution {
public int lengthOfLongestSubstring(String s) {

int len = s.length();
int len2 = len-1;
int i;
int c = 1;
int k = 0;
int l = 1;
int nulla= 0;
String ag = "";
ArrayList<String> sample = new ArrayList<String>();
ArrayList<Character> sample1 = new ArrayList<Character>();
for(i = 0; i<len2; i++){
char let = s.charAt(i);
char let1 = s.charAt(c);
if(sample1.contains(let)){
nulla++;
}else{

k = i;
l = c;
while(let != let1&& !sample1.contains(let)){
ag = ag + let;
k++;
l++;
let = s.charAt(k);
if(k == len2){
break;
}
let1 = s.charAt(l);
}

sample.add(ag);
ag = "";
if(let != let1){
sample1.add(let);
}
}
c++;
}
String stringa;
int len5;
int len6 = 0;
int maxlen= 0;
int lensa = sample.size();
for(int z = 0; z<lensa; z++){
stringa = sample.get(z);
len5 = stringa.length();
if(len5>=len6){
maxlen = len5;
}else{
maxlen = len6;
}
len6 = len5;
}
return maxlen;

}
}
 
Joined
Sep 21, 2022
Messages
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Please clarify "without repeating characters".

Do you mean only adjacent repeats, or any repeats?

Z is repeating in FIZZY.

Is Z repeating in TZINKZ?
 
Joined
Sep 21, 2022
Messages
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Your program is very hard to read.

Here's one way to do it.

The solution can be found in one pass through the string.

Let's say the alphabet is 26 letters. The longest substring with unique letters is somewhere from 1 to 26.

Let p and q be pointers into the string, initialised to 0.

Let X be an array, 'a' to 'z', initialised to -1. X('t') is the last known position of a t.

Let Y be an array, 1 to 26, initialised to false. Y holds the lengths found.

The substring from p to q, is unique.

Let's say you increment q, and q is now pointing to a 't'.

Code:
IF X('t') < p THEN
 p..q is still unique
 Y((q-p)+1) = true
ELSE
 p needs to shift
 p = X('t') + 1
ENDIF
X('t') = q
 
Joined
Sep 21, 2022
Messages
129
Reaction score
16
Sites like leetcode are odd.

Too formal to be a hobby, too unpaid to be a job.

Nothing wrong with programming exercises, but does the world really need 3205 of them?
 

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