diff --git a/Ch 1.Arrays And Strings/1.Is Unique/1. Is_unique.cpp b/Ch 1.Arrays And Strings/1.Is Unique/1. Is_unique.cpp
index 6118cc1..baab53b 100644
--- a/Ch 1.Arrays And Strings/1.Is Unique/1. Is_unique.cpp	
+++ b/Ch 1.Arrays And Strings/1.Is Unique/1. Is_unique.cpp	
@@ -2,6 +2,7 @@
 #include <vector>
 #include <iostream>
 #include <bitset>
+#include <map>
 #include <algorithm> // for sort() 
 
 using namespace std;
@@ -49,6 +50,20 @@ bool isUniqueChars_noDS( string str) {
 	return noRepeat;	
 }
 
+bool is_unique(string str){
+    map<char, int> character_counts;
+
+    int ctr = 0;
+    for (char c: str){
+        if (character_counts[c]==1){
+            return false;
+        } 
+        character_counts[c]=1;
+    }
+
+    return true;
+}
+
 int main(){
 		vector<string> words = {"abcde", "hello", "apple", "kite", "padle"};
 		for (auto word : words)