added Longest Substring Without Repeating Character in CPP

CPP/Longest_Substring_Without_Repeating_Characters.cpp

@@ -0,0 +1,60 @@
+/**
+ * @author: Jatin Garg 
+ * github(https://github.com/jatin-773762)
+ **/
+
+#include<bits/stdc++.h>
+using namespace std;
+
+/**
+ * Test Cases:
+ * 1) s= "abcabcbb" 
+ *    output: 3 (abc)
+ * 2) s="bbbbb"
+ *    output: 1 (b)
+ **/
+
+int lengthOfLongestSubstring(string s) {
+
+    // check if the string is empty or not
+    if(s.empty()){
+        return 0;
+    }
+    // vector to store the presence of character 
+    vector<bool> vis(256);
+    for(int i=0;i<256;i++){
+        vis[i]=false;
+    }
+    int ans=1;
+    int count=0;
+    for(int i=0;i<s.length();i++){
+        for(int i=0;i<256;i++){
+            vis[i]=false;
+        }
+        vis[s[i]]=true;
+        int j;
+        for(j=i+1;j<s.length();j++){
+            if(vis[s[j]]==false){
+                vis[s[j]]=true;
+                continue;
+            }
+            // if the character in substring repeats the loop breaks
+            break;
+        }   
+        // "j-i" is the length of the current substring
+        ans = max(ans,j-i);
+    }
+    return ans;
+
+}
+
+int main(){
+
+
+    string s;
+    // input string
+    cin>>s;
+
+    // prints the length of the longest substring with no repeating characters
+    cout<<lengthOfLongestSubstring(s);
+}