feat: added AllUniques program in Strings

Author: prathameshkurunkar7

String/AllUniques.cpp

@@ -0,0 +1,46 @@
+// An algorithm to check if a string has all unique characters.
+// Sample Input-1: Hello
+// Sample Output-2: All Characters are not Unique
+
+// Sample Input-1: World
+// Sample Output-2: All Characters are Unique
+
+
+#include<bits/stdc++.h>
+using namespace std;
+
+// time complexity = O(n)
+// 128-character alphabet set
+bool isAllUnique(string st)
+{
+    if(st.length()>128)
+    return false;
+
+    // initialize vector to zero flag
+    vector<bool> char_set(128,0);
+    int val;
+    for (int i = 0; i < st.length(); i++)
+    {
+        val = st.at(i);
+        if(char_set[val])
+        {
+            // already found this character
+            return false;
+        }
+
+        char_set[val] = true;
+    }
+    return true;
+}
+
+int main()
+{
+    string st;
+    getline(cin,st);
+    if(isAllUnique(st)){
+        cout<<"All Characters are Unique"<<endl;
+    }else{
+        cout<<"All Characters are not Unique"<<endl;
+    }
+    return 0;
+}