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3. Longest Substring Without Repeating Characters

Given a string s, find the length of the longest substring without repeating characters.

  • Example 1: 
    ​​  Input: s = "abcabcbb"
​​  Output: 3
​​  Explanation: The answer is "abc", with the length of 3.
  • Example 2: 
    ​​  Input: s = "bbbbb"
​​  Output: 1
​​  Explanation: The answer is "b", with the length of 1.
  • Example 3: 
    ​​  Input: s = "pwwkew"
​​  Output: 3
​​  Explanation: The answer is "wke", with the length of 3.
​​  Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.
  • Example 4: 
    ​​  Input: s = ""
​​  Output: 0
  • Constraints: 
    ​​​​0 <= s.length <= 5 * 104
​​​​s consists of English letters, digits, symbols and spaces.

C














































#include <stdlib.h>
#include <stdio.h>

//3. Longest Substring Without Repeating Characters
int lengthOfLongestSubstring(char* s) {
    int max = 0;
    int temp_max = 0;
    int current = 0;
    int repeating_char = 0;
    int new_start = 0;
    int flag = 0;
    if (s[current] == '\0') return 0;
    while (s[current] != '\0') {
        for (repeating_char = current - 1; repeating_char >= new_start; repeating_char--) {
            if (s[repeating_char] == s[current]) {
                flag = 1;
                break;
            }
        }
        if (flag == 0) {
            temp_max++;
        }
        else {
            new_start = repeating_char + 1;
            temp_max = current - new_start + 1;
            flag = 0;
        }
        if (temp_max > max)	max = temp_max;
        current++;
    }
    return max;
}


void main() {

    //3. Longest Substring Without Repeating Characters
    
    char* s = (char*)malloc(sizeof(char) * 10);
    s = "abcabcbb";
    //printf("%s\n", s);
    printf("%d\n", lengthOfLongestSubstring(s));
    

}

C++

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