feat: Add method for find first non-repeated character from string

JavaDsaWithTest/src/main/java/org/practice/dsa/strings/FindFirstNonRepeatedCharacter.java

@@ -0,0 +1,22 @@
+package org.practice.dsa.strings;
+
+public class FindFirstNonRepeatedCharacter {
+    public static void main(String[] args) {
+        System.out.println(findFirstNonRepeated("swiss"));
+    }
+
+    public static Character findFirstNonRepeated(String str) {
+        int[] freq = new int[256];
+
+        for (char c: str.toCharArray()) {
+            freq[c]++;
+        }
+
+        for (char c: str.toCharArray()) {
+            if (freq[c] == 1) {
+                return c;
+            }
+        }
+        return null;
+    }
+}