Add finding longest substring without repeating chars problem

Author: sudheerj

src/java1/algorithms/strings/longestSubstringWithoutRepeatingChar.java

@@ -0,0 +1,29 @@
+// Sliding window: TC: O(n), SC: O(n)
+package java1.algorithms.strings;
+
+import java.util.HashSet;
+
+public class longestSubstringWithoutRepeatingChar {
+    private static int longestSubstringLengthWithoutRepeatingChar(String str) {
+        HashSet<Character> hashset = new HashSet<>();
+        int left = 0, max = 0;
+    
+        for(int right = 0; right < str.length(); right++) {
+            while(hashset.contains(str.charAt(right))){
+                hashset.remove(str.charAt(left));
+                left++;
+            }
+            hashset.add(str.charAt(right));
+            max = Math.max(max, hashset.size());
+        }
+        return max;
+    }
+
+    public static void main(String[] args) {
+        String string1 = "abcabcbbaa";
+        System.out.println(longestSubstringLengthWithoutRepeatingChar(string1));
+        String string2 = "aaaaaaa";
+        System.out.println(longestSubstringLengthWithoutRepeatingChar(string2));
+    }
+    
+}

src/javascript/algorithms/strings/longestSubstringWithoutRepeatingChar.js

@@ -0,0 +1,20 @@
+// Sliding window: TC: O(n), SC: O(n)
+function longestSubstringLengthWithoutRepeatingChar(string) {
+    let set = new Set();
+    let left = max = 0;
+
+    for(let right = 0; right < string.length; right++) {
+        while(set.has(string[right])) {
+            set.delete(string[left]);
+            left++;
+        }
+        set.add(string[right]);
+        max = Math.max(max, set.size);
+    }
+    return max;
+}
+
+let string1 = "abcabcbbaa";
+console.log(longestSubstringLengthWithoutRepeatingChar(string1));
+let string2 = "aaaaaaa";
+console.log(longestSubstringLengthWithoutRepeatingChar(string2));