Create Longest_Substring_Without_Repeating_Characters.cpp

Solved-Problems/Longest_Substring_Without_Repeating_Characters/Longest_Substring_Without_Repeating_Characters.cpp

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+#include <iostream>
+#include <unordered_map>
+#include <string>
+using namespace std;
+
+// Function to find the length of the longest substring without repeating characters
+int lengthOfLongestSubstring(const string &s) {
+    unordered_map<char, int> charIndexMap;
+    int maxLength = 0;
+    int start = 0;
+
+    for (int end = 0; end < s.length(); end++) {
+        char currentChar = s[end];
+
+        // If the character is already in the map and is within the current window
+        if (charIndexMap.find(currentChar) != charIndexMap.end() && charIndexMap[currentChar] >= start) {
+            start = charIndexMap[currentChar] + 1;
+        }
+
+        // Update the last seen index of the current character
+        charIndexMap[currentChar] = end;
+
+        // Calculate the max length of substring
+        maxLength = max(maxLength, end - start + 1);
+    }
+    return maxLength;
+}
+
+int main() {
+    string input;
+    cout << "Enter a string: ";
+    cin >> input;
+
+    int result = lengthOfLongestSubstring(input);
+    cout << "The length of the longest substring without repeating characters is: " << result << endl;
+
+    return 0;
+}
+
+/*
+Example:
+Input: "abcabcbb"
+Explanation:
+- The longest substring without repeating characters is "abc", which has a length of 3.
+- As we iterate through the string:
+    - Start with "a" -> length 1
+    - Add "b" -> "ab" -> length 2
+    - Add "c" -> "abc" -> length 3
+    - "a" repeats, so move the start to the next character -> "bca" (length still 3)
+    - Continue until the end, with the longest substring remaining "abc".
+Output: 3
+
+Input: "bbbbb"
+Explanation:
+- The longest substring without repeating characters is "b", which has a length of 1.
+Output: 1
+*/