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src/TechInterview/FirstNonRepeated.java

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+/***
+
+Given a string s consisting of lowercase Latin Letters, find the first non repeating character in s.
+
+Input:
+
+The first line contains T denoting the number of testcases. Then follows description of testcases.
+Each case begins with a single integer N denoting the length of string. The next line contains the string s.
+
+Output:
+
+
+ For each testcase, print the first non repeating character present in string.
+
+ Print -1 if there is no non repeating character.
+
+***/
+
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+class FirstNonRepeated {
+	public static void main (String[] args) {
+
+
+		Scanner sc = new Scanner(System.in);
+		int t = sc.nextInt();
+		while(t-->0)
+		{
+		    Map<Character,Integer> map= new HashMap<>();
+		    int n = sc.nextInt();
+		    String s = sc.next();
+
+		    for(int i=0;i<n;i++)
+		    {
+		        if(map.containsKey(s.charAt(i)))
+		        map.put(s.charAt(i),map.get(s.charAt(i))+1);
+		        else
+		        map.put(s.charAt(i),1);
+		    }
+		    int check = 0;
+		    for(int i=0;i<n;i++)
+		    {
+		        if(map.get(s.charAt(i))==1)
+		        {
+		            System.out.println(s.charAt(i));
+		            check = 1;
+		            break;
+		        }
+		    }
+		    if(check == 0)
+		    System.out.println(-1);
+		}
+	}
+}