Add files via upload

Check the longest substring without repeating character

Longest_Substring.cpp

@@ -0,0 +1,18 @@
+class Solution {
+public:
+    int lengthOfLongestSubstring(string s) {
+
+        unordered_map<char,int> index;
+        int start=0,res=0;
+        for(int i=0;i<s.length();i++){
+
+            if (index.find(s[i]) != index.end() && index[s[i]] >= start)
+                 start = index[s[i]] + 1;
+
+            index[s[i]] = i;
+            res=max(res,i-start+1);
+        }
+
+        return res;
+    }
+};